Thanks in part to screening programs, death rates from breast cancer and cervical cancer have dropped dramatically in recent years.
"For certain types of cancer, screenings can detect a malignancy in its earliest stages, when it is more easily and successfully treated," says Judy Garber, MD, MPH, the director of Dana-Farber's Center for Cancer Genetics and Prevention. Deciding when to begin – and end – these screenings is not so straightforward.
While mammography is not perfect, it is the best screening tool currently available, says Eric Winer, MD, the director of the Breast Oncology Program at the Susan F. Smith Center for Women's Cancers at Dana-Farber. There is, however, considerable controversy regarding the age at which you should begin getting mammograms.
In 2009, the U.S. Preventive Services Task Force (USPSTF) recommended that, beginning at age 50, women should have a mammogram every two years, and that more evidence is needed to make a recommendation for or against screening after age 74. But the American Cancer Society (ACS) advises women to begin routine annual screening at age 40 and continue for as long as they remain in good health.
Dana-Farber experts say that only women at highest risk for breast cancer should begin mammography before age 40. After age 40, you can have an annual mammogram, based on your preferences and your doctor's recommendations. All women should begin yearly screening at age 50.
The American Congress of Obstetricians and Gynecologists, ACS, and USPSTF recently updated their guidelines for cervical cancer screening as well. They agree on several main points. In general, screening with Pap tests should start at age 21 in otherwise healthy women and continue every year or two until age 30. Then, women with at least three normal Pap tests may undergo Pap testing every three years, with or without co-testing for high-risk HPV, the virus that causes some cervical cancers.
If you have had normal lifetime screening, you may discontinue Pap tests between ages 65 and 70, but should still have routine gynecologic care. If you have never been screened, or have a history of high-grade dysplasia (a condition in which cells grow abnormally on the surface of the cervix), you are at highest risk of developing cervical cancer and should receive ongoing screening regardless of your age.
Dana-Farber breast and cervical cancer specialists encourage you to speak with your physician about appropriate screening based on your age, medical history, and risk factors.
Human cells have about 22,000 genes, which consist of DNA packed into chromosomes inside the cell nucleus. Genes control a wide range of functions, including cell growth and division. If DNA is damaged during a cell's life, certain genes work to repair the damage. Over time, however, those repair genes themselves may become ineffective, allowing DNA damage to accumulate.
If a cell acquires enough errors or mutations in certain genes, it may become cancerous – able to grow and divide without control. Such mutated genes exist only within the cancer itself, not the rest of the body. For that reason, they make excellent targets for so-called "smart" drugs that take aim at specific mutations.
The advantage of such drugs is that they can attack cancer cells while producing less harm to normal cells than traditional chemotherapy. Genetic defects that appear only in cancer cells are known as "somatic" mutations.
Other mutations in cancer are known as "germline." These are inherited from a parent or arise early in fetal development and are found in every cell of affected individuals.
"You inherit two copies of most genes in your body – one from your mother and one from your father," explains Judy Garber, MD, MPH, director of the Center for Cancer Genetics and Prevention at Dana-Farber. "If you have a germline mutation in one copy of a particular gene, the other copy would be normal."
It generally requires mutations in both copies for cancer to occur. People born with a mutation in one copy are likely to acquire a mutation in the other more quickly than those who begin life without these mutations – much as a baseball batter with one strike will probably reach a two-strike count faster than a batter with no strikes.
Scientists have discovered a variety of such cancer-susceptibility genes – such as BRCA1 and BRCA2. In addition, specialists can screen people with a family history of cancer to determine if they carry mutations in these genes.
Cancer research is concerned with both varieties of mutation. Some scientists are looking for somatic mutations associated with cancer so they can develop new targeted therapies, while others are tracking potential germline mutations in families where cancer has run like a thread through the generations.
The Profile research project in cancer genomics launched last year by Dana-Farber and Brigham and Women's Hospital is concerned with both types of mutations. In one part of the project, adult patients can have their leftover tumor tissue screened for nearly 500 somatic mutations involved in cancer.
In another part, they can donate normal cells – from a simple cheek swab or blood draw – for germline studies of genes that may predispose people to developing certain cancers.
Turning Point 2012
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