Early detection screening​

Early detection screening​


Regular mammography is often used to detect breast cancer at an early stage when treatment may be more effective.  Studies have shown that early detection saves lives and increases treatment options. Recent research from Sweden reported that screening has limited or no impact on breast cancer mortality among women aged 40-69 (according to a study published July 17 in the Journal of The National Cancer Institute).  Recent studies have shown that magnetic resonance imaging (MRI) appears to be more sensitive than mammography in detecting tumors in women with an inherited susceptibility to breast cancer. Thermography has also shown promise as part of the diagnostic process.

Colon and Rectum

Beginning at age 50, men and women who are at average risk for developing colorectal cancer should begin screening.  Screening can result in the detection and removal of colorectal polyps before they become cancerous as well as the detection of cancer that is at an early stage. Screening reduces the mortality both by decreasing incidence and by detecting a higher proportion of cancers at early, more treatable stages.  Screening includes various blood tests; flexible sigmoidoscopy; barium enema; and colonoscopy.


Because symptoms often resemble those of other, less serious conditions, leukaemia can be difficult to diagnose early.  When a physician does suspect leukaemia, diagnosis can be made using blood tests and a bone marrow biopsy.


Efforts at early detection have not yet been demonstrated to reduce mortality.  Chest x-ray, analysis of cells in sputum, and fibreoptic examination of the bronchial passages have shown limited effectiveness in improving survival.  Newer tests, such as low-dose spiral computed tomography (CT) scans and molecular markers in sputum, have produced promising results in detecting lung cancers at earlier, more operable stages when survival is better.  However, there are considerable risks associated with lung biopsy and surgery that must be considered when evaluating the risks and benefits of screening.


Routine screening for women at average risk is not recommended because no sufficiently accurate screening test is currently available.  The pelvic examination can only occasionally detect ovarian cancer, generally when the disease is already in advanced stages.  However, the combination of a thorough pelvic exam, transvaginal ultrasound, and a blood test for the tumor marker CA125 should be offered to woman who are at high risk of ovarian cancer and to women who have symptoms.  For women at average risk, transvaginal ultrasound and testing for the tumor marker CA125 may help in diagnosis but are not used for routine screening.


At present there is no method for the early detection of pancreatic cancer and the early stages of the disease are usually asymptomatic.  Researchers are focusing on ways to diagnose pancreatic cancer before symptoms occur.


At this time, there are insufficient data to recommend for or against prostate cancer testing in men at average risk of developing the disease.  The American Cancer  Society recommends that beginning at age 50, the PSA blood test (which detects a protein made by the prostate called prostate-specific antigen) and the digital rectal examination should be offered to men at average risk.  Individuals at high risk of developing prostate cancer (African Americans or men with a strong family history) should begin screening at age 45.  All men should be given information about the benefits and limitations of testing so they can make informed decisions.


The best way to detect skin cancer early is to recognize changes in skin growths or the appearance of new growths.  Adults should examine their skin regularly. Suspicious lesions or progressive changes in a lesion’s appearance or size should be evaluated promptly by a physician. Melanomas often start as small, mole-like growths that increase in size and change colour.  A simple ABCD rule outlines the warning signals of the most common type of melanoma:  A is for asymmetry (one half of the mole does not match the other half); B is for border irregularity (the edges are ragged, notched, or blurred); C is for colour (the pigmentation is not uniform, with variable degrees of tan, brown, or black); D is for diameter greater than 6 millimetres (about the size of a pencil eraser).


Bladder cancer is diagnosed by examination of cells in the urine under a microscope and examination of the bladder wall with a cystoscope, a slender tube fitted with a lens and light that can be inserted through the urethra.  These tests are not recommended for screening people at average risk but are used for people at increased risk due to occupational exposure, or for follow-up after bladder cancer treatment to detect recurrent or new tumors.


The Pap test is a simple procedure in which a small sample of cells is collected from the cervix and examined under a microscope.  Pap tests are effective but not perfect.  Their results sometimes appear normal even when a woman has abnormal cells of the cervix, and likewise, sometimes appear abnormal when there are no abnormal lesions on the cervix.  DNA tests to detect HPV (human papillomavirus) strains associated with cervical cancer may be used in conjunction with the Pap test, particularly when results are equivocal.  Fortunately, most cervical precancers develop slowly, so nearly all cases can be prevented if a woman is screened regularly.


Most endometrial (body and lining of the uterus) cancer is diagnosed at an early stage because of postmenopausal bleeding.  Women are encouraged to report any unexpected bleeding or spotting to their physicians.  Annual screening for endometrial cancer with endometrial biopsy beginning at age 35 should be offered to women with or at risk for HNPCC (hereditary nonpolyposis colon cancer).