Some Frequently Asked Questions Related to Cancer

• What is cancer?
  Cancer is an abnormal growth of a body cell or group of cells. If it is not destroyed or removed, cancer can spread very rapidly, and eventually lead to death.

 

• What is the difference between normal and cancerous growth?
  There are billions of cells in the human body. Normally, they grow in a well-regulated pattern. When cancer sets in a group of cells suddenly starts multiplying haphazardly and forms a lump or "tumor".

 

 

• How many kinds of tumors are there?
  There are two kinds of tumors. Malignant, and benign. A benign tumor is more common, and is generally harmless. It doesn't grow beyond a certain limit, and it doesn't spread to other parts of the body.

  A malignant tumor on the other hand, never stops growing and can spread to other parts of the body. Cancer is the name given to a malignant growth.

 

 

• Is cancer contagious or infectious?
  No. Since cancer is not caused by a germ, it is not "catching", and cannot be transmitted from one person to another.

 

 

• Is cancer a blood disease?
  No, though cancer cells may move through the blood stream to another part of the body. Cancer can however develop in certain tissues which form the blood cells.

 

 

• How does cancer spread?
  In 3 ways:
  

  1. Cancer cells grow through the walls of blood vessels and are carried by the blood stream to other parts of the body.

  2. They enter the lymphatic stream and are carried to lymph glands.

  3. They grow directly from one tissue to another.

 

 

• How fast  does  cancer  grow?
  There is no definite rate of growth of cancer tissue, Some types will grow more in a few weeks than other types will, in several years.

 

 

• Is cancer a single disease?
  No. the term "cancer" includes all forms of malignant growth. Very many varieties are known. These have certain characteristics in common though such as uncontrolled growth a tendency to spread widely in the body and fatal termination if not treated early and adequately. They differ in certain characteristics, such as location in the body, microscopic appearance, and response to treatment. Their histories of development may be quite dissimilar and it is probable that the conditions which may precede them also differ greatly.

 

 

• How can you tell if you have cancer?
  The real tragedy about cancer is that it produces very minor symptoms at first. So you could have cancer --- and not know it. The best way to detect cancer is to have a regular yearly check-up.

 

 

• How  does a  doctor tell if growth  is cancerous?
  By performing a biopsy i.e. examining a small portion of the tissue under a microscope. In advanced cases, physical examination alone may reveal the diagnosis. But the chances of cure at this late stage, are very poor.

 

• Are cancer and leprosy related?
  No. Leprosy is caused by a germ. Both the symptoms and the treatment for the two diseases are entirely different.

 

   

• Is cancer a modern disease?
  No. Even as long ago as 3,000 B.C., Egyptian historians made references to "tumors and ulcers". Mummies from the Gizeb Pyramids were found to have cancer involving the bones.

 

• Are some people more prone to certain types of cancer?
  Yes. Your life-style may make you more prone to some cancers. E.g. cancers of the Colon, lungs and skin are common in Britain and U.S.A., while cancers involving the head and neck region are more common in India. In women, cancer of the breast and uterus are the commonest.

• What are your chances of getting cancer?
  One out of every 8 Indians gets cancer. In other words, there are about 15 to 18 lakh cancer patients in India alone. Though cancer can occur at any age, the incidence is higher after the age of 40 to 45.

 

 

• What causes cancer?
  Though it is very difficult to pinpoint any definite cause, certain substances, known as carcinogens, can definitely increase your chances of getting cancer. For instance, people who smoke or chew tobacco are more prone to mouth, throat and lung cancer.  Contrary to popular opinion, beedi smoking is twice as dangerous as cigarettes. Amongst other known causes are asbestos, arsenic, pitch, tar, ultra-violet rays. Continued irritation of tissues can lead to cancer.

 

 

• Is cancer caused by a germ?
  There is no scientific evidence that cancer is caused by a germ.

 

 

• Does cancer come from a single bruise?
  A type of bone cancer may rarely result from a single severe injury. A single injury to soft tissue, such as the breast, will not give rise to cancer.

 

 

•  What is the relation of food to cancer?
  In certain individuals, Vitamin B deficiency may result in changes in certain tissues, particularly of the mouth and lips, which may ultimately become cancerous. In general, however, so far as is known, no food or combination of foods has any influence on the cause or cure of cancer· but heavily fried food or abandoned red meat is today suspect. Green vegetables, cabbage may help in preventing certain cancers.

 

 

•  Will irregularity in eating cause cancer of the stomach?
  There is no scientific evidence that it will, since cancer of the stomach may occur in people who eat most regularly.

 

 

• Does eating hot food cause cancer?
  There is little evidence that the temperature of food is an important factor in the development of cancer.

 

• Does the use of alcohol bear any relation to cancer of the stomach?
  Not so far as is known. Alcohol may have an unfavorable effect on stomach tissues, but no more so than other substances taken along with food or drink.

 

   

• Is cancer hereditary?
  There are probably inherited tendencies that may lead to cancers of different types. The presence of cancer in one or both parents should be a cause for greater alertness in looking for and recognizing suspicious symptoms in the individual. Cancer however is not inherited except for one type of eye cancer known as Retinoblastoma.

Comment: " Whilst the actual cancers are not hereditary sometimes the reasons that the
cancers are able to get a grip are hereditary.
In the past 12 -18 months its become known that most cervical cancers can be
hereditary and passed down the female genes. It appears it does not get
passed through the male genes. If the defective gene is inherited then the
female is susceptible to the HPV16 virus which is carried by 85% of the male
population. Most females bodies are able to recognise this virus and
eliminate it. Those without the relevant gene cannot and are very likely to
develop some form of cervical abnormality which can lead to cancer. This is
a cancer which can be easily treated if caught early. If women are aware
that it can be hereditary then they can be checked regularly and hopefully
many lives would be saved.
It is also known that women with breast cancer  in the family can be
genetically predisposed to getting breast cancer themselves, and that's both
men and women. It is also now known that males descending from women with
breast cancer should be more alert to checking for prostrate cancer."

- sent in by:  Brenda Holday, 
Marketing Director
Enjoy Sports Travel Ltd, UK

• Can cancer be transmitted by kissing or casual contact between persons or between persons and animals?
  No. There is no record of cancer having been transmitted by kissing or by any contact, accidental or otherwise, between individuals or between persons and animals (such as pets).

 

 

• Do corns become cancerous?
  Cancer may occur in any tissue of the body, but a corn could not as a rule develop into cancer.

 

 

• Do freckles turn into cancer?
  Simple freckles do not. However, flat moles containing pigment of a bluish-black colour and looking like dark freckles, may become cancerous and should be checked periodically.

 

 

• Do piles turn into cancer?
  No. Piles or hemorrhoids are merely enlarged veins in the rectal wall. Cancer is occasionally found in the tissue above the hemorrhoids, so "bleeding piles" should be examined carefully to determine whether cancer is also present. Rectal bleeding can occur due to cancer.

 

 

• Can one's mental condition influence the course of cancer?
  Not so far as is known. Cancer is a disease of body cells. One's mental condition has no effect on the course of the disease since this malignant change is apparently due to physical rather than mental processes.

 

 

• Does radiation cause cancer?
  Indiscriminate use of X-rays frequently may increase your chances of getting cancer.

 

 

• How can one guard against cancer?
  By preventing, so far as possible, prolonged irritation of any part of the body. Specifically, protection from overexposure to the sun and wind, prompt repair of all birth injuries to the womb, permitting the breasts to function normally early in life, repair of jagged teeth, avoidance of ill-fitting dental plates, avoidance of tobacco, correction of chronic constipation in short, elimination of unnecessary abuse of any tissue is a common sense method of helping to guard against cancer.

 

 

• What is meant by a "pre-cancerous lesion"?
  Any abnormal condition that, if permitted to continue, may develop into cancer with passage of time

 

 

• What are some of the more important pre-cancerous lesions?
  White spots on mucous (lining) membranes, especially of the mouth; dry, scaly, itching patches on the skin, particularly the face; sores caused by jagged teeth and ill-fitting dental plates; dark colored moles subject to irritation; unrepaired injuries due to childbirth. These should all be investigated by a physician and adequately treated.

 

 

• What precautions should be taken to avoid cancer of the mouth?
  Keep the mouth clean. Have jagged teeth filed or removed. Do not use an ill-fitting dental plate, which causes a sore on the gums or cheek. If white spots appear in the mouth or on the tongue, stop the use of tobacco and see a doctor.

 

 

• What precautions should be taken to avoid cancer of the Skin?
  Dark colored moles and warts, if subject to irritation, should be removed. Itching, scaly patches on the skin should be treated before they become open sores. Fair-skinned people, especially, should avoid overexposure to direct sun rays. Recurrent fever blisters on the lip should be carefully examined. Keep the skin clean.

 

 

• Should all moles be removed?
  No. A flat colorless mole is probably as harmless as a freckle. Bluish-black hairless moles, especially when subject to irritation, should be removed. Any mole or wart showing changes in size or colour or if bleeding should be promptly and completely removed and the tissue examined by a pathologist to determine if cancer is present.

 

 

• Can immunity to cancer be acquired as with diptheria or typhoid fever?
  Production of immunity is possible only in diseases caused by germs. As cancer is not caused by germs, immunity cannot be developed against it as far as our knowledge goes today.

 

 

• Why do many people wait before consulting a physician when cancer may be present or suspected?
  Primarily because of fear or ignorance of the signs of cancer and of the vital importance of securing treatment early. Some people also think there is a social disgrace in having cancer and so hide the fact from their physicians and often from friends and relatives. This is not a justifiable attitude.

 

 

• Can a tuberculous person ever have cancer?
  He can. The presence of tuberculosis or any other disease gives no assurance that cancer may not also develop.

 

 

• Why don't the white corpuscles in the blood kill cancer?
  The chief function of white blood corpuscles is to protect the body against bacteria or germs. They kill germs and combat infection. Current research is being undertaken to promote such activity by certain kinds of white blood corpuscles.

 

 

• How can we control cancer?
  By a prompt visit to a physician, when suspicious signs or symptoms appear. Intelligent alertness by the individual may well save his life. By having complete, annual physical examinations, as a routine. Women over 35 should be examined twice a year. By confirming diagnosis at the earliest possible moment, followed by adequate treatment. By a widespread knowledge, both lay and professional, of the character of cancer, its causes, methods of spread, and by recognizing the value of early diagnosis and adequate treatment, as the means of protection.

 

 

• How can you tell if you have cancer without seeing a doctor?
  You cannot. A regular thorough physical check-up is your best guard against cancer, plus an examination when one of the seven danger signals or warnings appears. You are the first line of defense against cancer because, you alone, can recognize a danger signal and heed its warning.

 

• What are some of the early signs of cancer?
  There are seven common ones. They are often called the Seven Danger Signals of Cancer:

  1. Change in bowel or bladder habits.

  2. A Sore that does not heal.

  3. Unusual bleeding or discharge.

  4. Thickening or lump in breast or elsewhere.

  5. Indigestion or difficulty in swallowing.

  6. Obvious change in wart or mole.

  7. Nagging cough or hoarseness.

  You should at once consult a doctor upon the appearance of any sign.

 

   

• Is pain an early symptom of cancer?
  No, except in a cancer involving bone or nerve tissue. Pain usually is a late symptom and when it occurs, the growth is often far advanced.

 

   

• Why should cancer be diagnosed and treated early?
  The sooner it is found it is less likely to have spread to other parts of the body.

 

 

• How long is it safe to wait before consulting a physician?
  Any delay is dangerous. Go at once to a doctor and ask for a thorough examination.

 

 

• Why are periodic examinations necessary?
  The earlier a cancer is treated the greater the chance of a cure. Through periodic examinations cancer may be detected in its early stages, before the individual has noticed any sign or symptom in himself.

 

 

• Where can you get a check-up?
  The Indian Cancer Society runs several check-up clinics. You can find out which is closest to you.

 

 

• What comprises a thorough check-up?
  Careful inspection of the entire body surface, heart, blood vessel and lung examinations. Examination by sight and touch of accessible organs, such as the mouth, nostrils, ears, throat, chest, breasts, womb, and rectum. Examinations of stomach and intestines by X-ray when indicated. Microscopic examination of blood, urine, and any suspected tissue. In women, special examination of the breasts. Other examinations as indicated, such as of the eye, bladder and prostate by appropriate methods.

 

 

• Is the check-up painful?
  The check-up takes only an hour and is completely painless. You may phone and get an appointment.

 

 

• What is mammography?
  Mammography is a special X-ray examination of the breast tissues.

 

 

• What is a pap smear?
  The Papanicolaou Test, (or Pap smear) is in fact a microscopic examination of the cells exfoliated from the uterus and cervix. The doctor takes a swab from the tissue surface for examination. This test warns patients of the presence of cancer even as tiny as a pin-head or gives evidence of a lesion which is a pre-cursor of cancer.

 

• Is bleeding always a sign of cancer?
  No, but bleeding should be promptly and carefully investigated, to determine if it is due to cancer. A small percentage of bleeding nipples are due to cancer. Bleeding from other body openings, such as rectum or bladder, should be carefully investigated to rule out cancer. Unnatural vaginal bleeding, especially after the change of life can be a very suspicious sign of cancer.

 

   

• Does blood in bowel movements indicate cancer?
  Movements streaked with bright blood or the occurrence of black or "tarry" stools should lead to prompt and thorough investigation. The assumption that rectal bleeding is merely due to hemorrhoids, or piles, is most dangerous, since such bleeding may be due to a multiplicity of causes, including cancer, which require prompt treatment.

 

 

• Does blood in the urine indicate cancer?
  It may, but it may also be caused by conditions other than cancer. A careful examination is essential to rule out cancer.

 

 

• Is it true that cancer generally develops among people in poor health?
  There is no known relation between the status of one's health and the development of cancer. Regular checkups provide the best safeguard against cancer as well as against various other diseases.

 

 

• How can we diagnose cancer of the stomach?
  The best method is an X-ray examination. The outline of the interior of the stomach when filled with a radio-opaque material such as barium sulphate, can give clues to the presence of cancer. Chemical tests of stomach contents are also of value. Only in late stages a lump may be felt through the body wall.

 

 

• How are cancers in the head and neck region diagnosed?
  The most important test is an examination of the mouth and throat with a head light and mirror, to check for ulcerations, growths and white patches on the lining membrane called mucosa. A "Biopsy" specimen is always taken to confirm the clinical diagnosis. This is then reported by an experienced Histo-pathologist in the laboratory. In India nearly 40% of Cancer arises in this region, in men.

 

 

• What techniques are used to detect cancer?
  Xerographs, mammographs, thermographs, CAT Scans, etc. are some of the highly sophisticated methods of cancer detection, in addition to clinical and pathological examinations.

 

 

• How should cancer be treated?
  By surgery, chemotherapy, X-ray or cobalt therapy and high density electron therapy or a combination of all these in the earliest possible stage of the disease. All these methods are available in India at various Hospitals.

 

 

• Are X-ray treatments good for all kinds of cancer?
  No. Treatment depends on type and location of the growth. Some cancers will not respond to X-ray or radium treatment but must be treated by surgery or with hormones and Radioactive isotopes.

 

 

• What is the difference in the action of X-rays and radium or cancer tissue?
  There is no essential difference. When correctly used both will destroy cancer cells without seriously injuring the normal cells with which they come in contact.

 

How are radium or radioactive isotopes used? Radium in hollow needles radioactive isotope wires are inserted into the cancerous growth are in the tissue surrounding it, and removed after treatment is concluded. Radium or radioactive isotopes in suitable containers may also he placed in contact with the growth as in cancer of the skin or cervix. In larger quantities they may be used at a distance from the body, the rays passing through an opening in the container into the cancerous growth. How effective is surgery? Surgery is most effective in the early stages when cancer has not yet spread. Major advances in plastic and reconstructive surgery, and anaesthesiology have ensured a very high degree of success. What is chemotherapy? Chemotherapy implies treatment with anticancer drugs and injections. Today we have a large number of highly effective drugs for cancer control. Can the spread of cancer be stopped or retarded temporarily? At times only. Certain types of cancerous growths, which can not be expected to be curable, may be controlled temporarily by proper treatment. Sooner or later, however, these growths may fail to respond to further treatment. What should you do if you think you may have cancer? Report at once for a thorough physical examination. Is cancer curable? More than 80% of cancers today are completely curable if treated early. At times, however, cures have been obtained after the cancers have been present for a long time. The type of cancer always has an important bearing on its curability. Is it ever possible to state that a cancer has been completely cured? If so, how much time must pass before the "cure" is recognized? After a cancer patient has been treated and has remained free of recurrence of disease for a period of five years, the chances for reappearance of the tumor are extremely small. (In a few rare instances however cancer has recurred ten or twenty years later, so that a semi-annual physical examination is a must for cancer patients). If you have been cured of cancer, can you develop another cancer? In the same place? In some other part of the body? Yes. Regardless of a patient's past medical history, including the successful treatment of a previous cancer, he/she should be examined at regular intervals. Because of the tendency for cancer to  reappear at the place of a previously existing growth or nearby, a patient should have a regular follow-up at least every six months. A new cancer may also appear at in another part of the body. Is there any known vaccine cure for cancer? No. A vaccine is of value only against a disease due to a germ. Cancer is not caused by a germ; therefore, serums are of no value in its treatment. Is it ever safe to rely on salves to "cure" cancer? No. No a paste or salve can not penetrate the tissues far enough to destroy deep-seated cancer cells. Is there any chemical that destroys cancerous tissue? There is some evidence that a few chemical substances such as the nitrogen mustards and other chemicals can destroy certain kinds of cancers. This treatment is known as chemotherapy.     Will hormones cure cancer? There is evidence today to indicate that treatment with certain hormones may prolong life, and alleviate pain and suffering in certain breast and uterine cancers and in prostate cancers.     What is Immunotherapy? Immunotherapy is new development based on the theory that the human body can be taught to defend itself against diseases including cancer. What is the latest and most successful of the recently reported cancer treatments? While many "cures" are constantly being evaluated by various laboratories, surgery, X-ray treatment, and chemotherapy remain the chief weapons in the physicians' fight to cure cancer. Certain hormones and isotopes also offer some promise of assistance in their fight but it is much too early to claim that they can be called 'cures". Is any real process being made in cancer research? Along what lines? Real progress is being made in cancer research, which has thrown much new light on normal and abnormal growth processes. However, the goal of finding the cause of cancer and thus its prevention is still in the future. Various avenues of investigations have recently opened up on all sides: in chemistry by a study of the hormones and chemicals and the complex role they play in cancer; in physics by application of radioactive materials and the development of X-rays of very high voltages; in surgery by more radical excision of tumors; and of through a study of enzymes, genetics, nutrition, cytochemistry, etc. Scientific disciplines of various types are being utilized to study the complex nature of cancer. What are your chances of getting cured? More than 80% of the patients treated adequately in the early stages can be cured. Your chances of recovery are excellent, if you report for treatment very early after cancer has arisen. Can you lead a normal life after cancer? The sooner you come for treatment, the better the quality of life after cancer. Most cancer patients can return to their normal lives, even during treatment. Are cancers in men and women different? There are no fundamental differences in cancers appearing in men and women. What forms of cancer are more common among men than women? Cancer of the mouth, throat, gullet, stomach, rectum, larynx, lung, kidney, bladder, skin and brain are all more common in men than in women. Does smoking or tobacco and paan chewing cause cancer? Smoking and chewing are known to cause cancer of the mouth, throat, bladder, lungs etc. Therefore, it is best to play it safe and, if you smoke or chew make every effort to stop Can cancer result from sexual intercourse? No. There is no known relationship between cancer and sexual activity on the part of the male or female. However women who have multiple sexual partners run a greater risk of getting cervix cancer.     Is cancer of the prostate common? At what age does it generally occur? Yes, cancer of the prostate is one of the most common forms of cancer in older men. Men should be on guard against this form of cancer especially as they approach 60. A thorough physical examination, including a rectal examination, is the only way to discover this hidden cancer early enough for cure.     Do more women than men die of cancer? No. The misconception that cancer is primarily a woman's disease is due to the frequency of cancer of the breast and cancer of the reproductive organs in women, in comparison with the more varied occurrence of cancer in men. Cancer in men often occurs in the less accessible areas of the body and is sometimes more difficult to diagnose and treat than cancer in women. Does cancer occur more frequently among married or unmarried women? Reports from death certificates show that above the age of 40, the cancer death rate is higher among single women than among married women of the same ages. Single women have higher death rates from cancer of the breast and married women have more cancer of the uterus. Physicians believe that having the first child around the age of 20 is a preventive against cancer of the breast and that injury at childbirth or having multiple sexual partners increases the risk of cancer of the uterus. Is there danger in watching a lump in the breast to see what happens? Yes, a very grave danger. Time is the most important factor in the control of cancer and waiting to "see what happens" may permit a curable cancer to become incurable by preventing it to spread to other tissues. Are all breast lumps cancerous? No, only a small percentage of lumps are cancerous. A careful pathological examination of the excised lump can definitely determine if it is due to cancer. What precautions should be taken to avoid cancer of the breast? Do not wear garments that press the breast tissue tightly against the chest wall. Every woman should have her breasts examined semiannually by a physician. She should request her physician to instruct her in the proper technique for examining her own  breasts in the erect and reclining positions and should examine her breasts once a month shortly after her "period". How should you examine your breasts? Sit or stand in front of a mirror, with your arms relaxed at your sides, and examine your breasts carefully for any changes in size and shape. Look for any puckering or dimpling of the skin, and for any discharge or change in the nipples. Compare one breast with the other. Raise both your arms over your head, and look for exactly the same changes. See if there's been any change since you last examined your breasts. Note :From Step 3 to Step 8, you should feel for a lump or thickening in the breast tissues. Lie down on your bed, or on the floor, put a pillow or a bath towel under your left shoulder, and place your left hand under your head. With the fingers of your right hand held together flat, press gently but firmly with small circular motions to feel the inner, upper quarter of your left breast, starting at your breastbone and going outward toward the nipple line. Also feel the area around the nipple. With the same gentle pressure next feel the lower, inner parts of your breast. Now bring your left arm down to your side, and still using the flat part of your fingers, feel under your armpit. Use the same gentle pressure to feel the upper, outer quarter of your breast from the nipple line to where your arm is resting. And finally, feel the lower, outer section of your breast, proceeding from the outer part to the nipple. Repeat the entire procedure, from Step 3 as described above, for the right breast. What precautions should be taken to avoid cancer of the uterus (womb)? Have all birth injuries repaired soon after they occur. Have all unnatural vaginal discharges investigated. Up to the age of thirty-five have an annual examination; thereafter a semi-annual one. Bleeding after the change of life calls for a physician's examination at once. Avoid multiple sex partners. Do uterine fibroids ever become cancerous? Fibroid tumors only very rarely undergo malignant change Can cancer develop in children? At what age? No age is free from cancer. Certain forms of cancer, especially of the eyes and blood are most occasionally found in young children.     If a parent dies of cancer are the children more likely to have the disease? The answer is no. In many families where a parent has had cancer, the disease does not appear in the children. Again, a person whose family has no record of cancer may develop it. A tendency to develop breast cancer however runs in families. Does cancer develop more quickly in children than in older people? The rate of growth at any age depends upon the type of cancer, though cancer does grow faster at younger ages. If detected in time, can cancer in a child be cured more quickly than in an adult? The cure of cancer has little relationship with age. It depends upon the extent of growth at the time it is detected, and the adequacy of the treatment given as well as the type of cancer detected. How can cancer deaths be reduced? By four means: Early diagnosis; the responsibility of the patient in having himself/herself regularly checked by a physician; and the responsibility of the physician in recognizing the possibility of cancer and referring for further diagnostic procedures and proper treatment. Adequate and prompt treatment. Discoveries of newer and more effective means of treatment. The ultimate discovery of the various causes of cancer. These last two will come from research laboratories and clinical investigators. From these stem the basic principles of the cancer control programme of education, research and service of the Indian Cancer Society. Is there any disgrace in having cancer? There is no more disgrace in having cancer than in having a broken arm. Does cancer usually cost more to cure, than other major diseases? It often does. Here again, it depends upon the type of cancer you have and how much must be done to treat it. Many hospitals provide free treatment to those who cannot afford to pay. Why are quacks dangerous? For the following reasons, among others: Few quacks are medically trained; therefore, they have no fundamental knowledge about cancer. They cause the patient to lose valuable time that should be used to obtain correct treatment. The pastes and "medicines" used by quacks have no value in curing cancer. The quack takes the patient's money under false pretenses, thus depriving him of the means for obtaining competent treatment in time to enable him or her to be cured. How can I tell a quack from a reputable physician? If a person advertises a cure, guarantees a cure, or employs a method of diagnosis or treatment not generally accepted or endorsed by the medical profession, may he classed as a quack. No reputable, ethical physician will do any of these things. Is cancer frightening? Only if you neglect it. Today more and more people are not only winning their fight against cancer, they are also able to lead normal, active lives. Source : Indian Cancer Society