Cancer can produce many different symptoms, some subtle and some not at all subtle. Some symptoms develop early in the course of cancer and are therefore important warning signs that should be evaluated by a doctor. Other symptoms develop only after the cancer progress and are therefore not helpful in the early detection of cancer. Still other symptoms, such as nausea, loss of appetite, fatigue, and vomiting, may be the result of the cancer or its treatment, may be warning signs, or may event result from conditions other than cancer. Some symptoms occur with many or almost all cancers, and others are specific to the type of cancer and where it is growing.
Screening programs allow early detection and diagnosis of cancer. The earlier cancer is diagnosed, the more effective treatment is likely to be.
Symptoms of Cancer
At first, cancer, as a tiny mass of cells, produces no symptoms whatsoever. As a cancer grows, its physical presence can affect nearly tissues. Also, some cancers secrete certain substances or trigger immune reactions that cause symptoms in other parts of the body that are not near to the cancer (paraneoplastic syndromes).
Cancer affects nearly tissues by growing into or pushing on them, this irritating or compressing them. Irritation typically causes pain. Compression may keep tissues from performing their normal functions. For example, a bladder cancer or a cancerous lymph mode in the abdomen may compress the tube (ureter) connecting a kidney with the bladder, blocking the flow of urine. A lung cancer may block Airflow through one segment of a lung, causing partial lung collapse and predisposing to infection. Cancer anywhere may compress a blood vessel, shutting off blood flow or causing bleeding.
When cancer grows in an area with a lot of space, such as in the wall of the large intestine, it may not cause any symptoms until it becomes quite larger. In contrast, a cancer growing in a more restricted space, such as on a vocal cord, may cause symptoms (such as hoarseness) when it is relatively small. If a cancer spreads (metastasizes) to other parts of the body, the same local effects of irritation and compression eventually occur, but in the new location, so the symptoms may be quite different. Cancers that involve the membrane covering the lungs (pleura) or the baglike structure that surrounds the heart (pericardium) often ooze fluid, which collects around those organs; large fluid collections can interfere with breathing or the pumping of the heart.
Cancers are typically painless at first. As they grow, the first symptom is often a mild discomfort, which may steadily worsen into increasingly severe pain as the cancer enlarges. The pain may result from the cancer compressing or eroding into nerves or other structures. However, not all cancers cause severe pain. Similarly, lack of pain does not guarantee that a cancer is now growing or spreading.
At first, a cancer may bleed slightly because its calls are not well attached to each other and its blood vessels are fragile. Later, as the cancer enlarges and invades surrounding tissues, it may grow into a nearby blood vessel, causing bleeding. The bleeding may be slight and undetectable or detectable only with testing. Such is often the case in early stage colon cancer. Or, particularly with advanced cancer, the bleeding may be more significant, even massive and life threatening.
The site of the cancer determines the site of the bleeding. Cancer anywhere along the gastrointestinal tract can cause bleeding in the stool. Cancer anywhere along the urinary tract can cause bleeding in the urine. Other cancers can bleed into internal areas of the body. Bleeding into the lungs can cause the person to cough up blood.
Weight Loss and Fatigue
Commonly, a person with cancer experience weight loss and fatigue, which can worsen as the cancer progresses. Some people notice weight loss despite a good appetite. Others lost their appetite and may even become nauseated by food or have difficulty swallowing. They may become very thin; the loss of underlying fat is particularly noticeable in the face. People with advance d cancer are often very tired and sleep many hours a day. If anemia develops, these people may find that they feel tired or become short of breath with even slight activity.
Swollen lymph Nodes
As a cancer begins to spread around the body, it may first spread to nearby lymph nodes, which become swollen. The swollen lymph nodes may be painless or tender, and they may feel hard or rubbery. They may be freely moveable, or if the cancer is more advanced, they may be stuck to the skin above, to the deeper layers of tissue below, or to each other.
Cancer often results in depression. Depression can be related to the symptoms of the illness, a fear of dying, or a loss of independence. Additionally, some cancers may produce substances that directly cause depression by affecting the brain.
Neurologic and Muscular Symptoms
Cancer can grow into or compress nerves, causing any of several neurologic and muscular symptoms, including a change in sensation (such as tingling sensations) or muscle weakness. When a cancer grows in the brain, symptoms may be hard to pinpoint but can include confusion, dizziness, headaches, nausea, changes in vision, and seizures. Neurologic symptoms may also be part of paraneoplastic syndrome.
Cancer can compress or block structures, such as the airways in the lungs, causing shortness of breath, cough, or pneumonia. Shortness of breath can also occur when the cancer causes a large pleural effusion, bleeding into the lungs, or anemia.
Diagnosis of Cancer
Cancer is suspected based on a person’s symptoms, the results of a physical examination, and sometimes the results of screening tests. Occasionally, x0rays obtained for other reasons, such as an injury, show abnormalities that might be cancer. Confirmation that cancer is present requires that tests (termed diagnostic tests). After cancer is diagnosed, it is staged. Staging is a way of describing how advanced the cancer has become, including such criteria as how big it is and whether it has spread to neighboring tissues or more distantly to lymph nodes or other organs.
Screening For Cancer
Screening tests serve to detect the possibility that a cancer is present before symptoms occur. Screening tests usually are not definitive; results are confirmed or disproved with further examinations and tests. Diagnostic tests are performed once a doctor suspects that a person has cancer.
Although screening tests can help save lives, they can be costly and sometimes have psychologic or physical repercussions. Screening tests can produce false positive results – results that suggests a cancer is present when it actually is not. False-positive results can create undue psychologic stress and can lead to other tests that are expensive and risky. Screening tests can also produce false-negative results – results that show no hint of a cancer that is actually present. False-negative results lull people into a false sense of security. For those reasons, there are only a small number of screening tests that are considered reliable enough for doctors to use routinely.
Doctors determine whether a particularly person is at special risk for cancer because of age, sex, family history, previous history, or lifestyle before they choose to perform screening tests. The American Cancer Society has provide cancer screening guidelines that are widely used. Other groups have also developed screening guidelines. Sometimes recommendations vary among different groups, depending on how the groups’ experts weight the relative strength and importance of available scientific evidence .
In women, two of the most widely used screening tests are the papanicolaou (Pap) test to detect cervical cancer and mammography to detect breast cancer. Both screening tests have been successful in reducing the death rates from these cancers in certain age groups.
In men, prostate-specific antigen (PSA) levels in the blood may be used to screen for prostate cancer. PSA levels are high in men with prostate cancer, tut levels also are elevated in men with noncancerous (benign) enlargement of the prostate. As such, the main drawback to its use as a screening test is the large number of false-positive results, which generally lead to more invasive tests. Whether the PSA test should be used routinely to screen for prostate cancer is unresolved, with varying recommendations from different groups. Men over 50 should discuss the PSA test with their doctor