Radiation Therapy and Risk of Second Tumor
Although radiation is a known carcinogen (substance that causes cancer), researchers report in the Journal of Clinical Oncology that women treated with radiation therapy for breast cancer do not have an increased risk of developing a second cancerous tumor.
During a 20-year period, 1,029 patients with early breast cancer (stage I or II) underwent lumpectomy (removal of a breast tumor and some surrounding tissue) followed by radiation therapy. These patients were compared with 1,387 women who underwent mastectomy (removal of the entire breast) without radiation therapy. The patients in the two groups had similar stage of disease and prognosis.
Researchers found that the risk for a second cancerous tumor within 15 years was nearly identical for the two groups: 17.5 percent for the lumpectomy with radiation group and 19 percent for the mastectomy group. The risk for cancer in the opposite breast was 10 percent for each group. The risk for cancer elsewhere in the body was 11 percent in the lumpectomy with radiation group and 10 percent in the mastectomy group. They concluded that there was no increased risk for second tumors in patients undergoing lumpectomy with radiation therapy.
Although treatment with hormone therapy decreased the risk for a second breast tumor, the effect was not statistically significant. Similarly, patients age 45 years or younger in the mastectomy group had a 3 percent lower risk for developing a second breast tumor at 15 years than patients who had lumpectomy-radiation, but the finding was not statistically significant.
The researchers plan to continue following the women in the study in order to detect any difference in risk that may become apparent after a longer follow-up period.
Source: Journal of Clinical Oncology. June 2000. Volume 18, No. 12, pp. 2406-2412
Women's Attitudes About Mammography
Women who undergo screening mammography for detection of breast cancer run the risk of a false-positive result--an "abnormality" on the mammogram that, with further testing, is found to be noncancerous. According to a study published in the British Medical Journal, American women appear to be aware of false positives and accept them as a part of mammography screening.
For the study, women across the United States were randomly selected to receive a questionnaire by mail. The study included 479 women aged 18 to 97 years old who did not have a history of breast cancer. Most of the participants reported undergoing at least one mammogram, and most reported that they planned to have a mammogram within the next two years.
Ninety-nine percent of the women were aware that false-positive results would occur during ten years of screening beginning at age 60. Their average estimate of the chance of a false-positive result during this time frame of screening was 20 percent. The actual likelihood that a 60-year-old woman undergoing annual screening for ten years will have a false-positive result is higher: there is a 50 percent chance of having a false positive that leads to further testing and a 20 percent chance of a false positive that leads to biopsy.
Study participants were asked how many false positives would be acceptable for each life saved. Sixty-three percent reported that 500 or more false positives would be acceptable, and 37 percent said they would accept 10,000 or more. The actual estimated number of false positives for each life saved is between 30 and 200, far below what the women studied said they would tolerate.
Seventy-six (16 percent) of the women had personally had a false-positive result on a mammogram. Of these women, 71 percent reported that they would accept 500 or more false positives for each life saved, and 39 percent would tolerate 10,000 or more. Thirty-five percent reported wanting to take false positives into account when deciding on screening.
The women were aware that mammograms do not find all cancers. They predicted an average sensitivity for a single mammogram as 73 percent, which is lower than the actual reported sensitivity of 94 percent.
Researchers also questioned women about their knowledge of ductal carcinoma in situ (DCIS), a form of breast cancer that is only detected by mammography. Most cases of DCIS do not become invasive cancer and would have no effect on survival, even without treatment. Because it is not known which DCIS tumors will progress and which will not, almost all women found to have DCIS are treated, many unnecessarily.
Most of the women surveyed were not aware of the nature of DCIS. Only 7 percent were aware that mammography can detect noninvasive cancer. Sixty percent reported that such information would be relevant to have when deciding on screening mammography.
Source: British Medical Journal. June 17, 2000. Volume 320, pp. 1635-1640
New Drug Combination May Help Advanced Breast Cancer
Premenopausal women with advanced breast cancer who take a combination of drugs rather than either drug alone may live longer, according to a study published in the Journal of the National Cancer Institute.
From 1988 to 1995, 161 premenopausal women with advanced breast cancer--cancer that has metastasized, or spread to other parts of the body--were randomly assigned to receive tamoxifen, buserelin, or both medications. After seven years, 76 percent of the patients had died of breast cancer. Those treated with both drugs lived an average of 3.7 years. Those treated with tamoxifen alone lived 2.9 years, and those treated with buserelin alone lived 2.5 years. Women who received the combination of drugs also had a better response to treatment and lived longer without progression of disease.
Currently, premenopausal women with advanced breast cancer may be given tamoxifen alone, which prevents the hormone estrogen from feeding tumor cells.
Source: Journal of the National Cancer Institute. June 7, 2000. Volume 92, No. 11, pp. 903-911
DNA Testing and Prophylactic Surgery in High-Risk Women
Women who have one of the gene mutations known as BRCA1 and BRCA2 have a 55-85 percent lifetime risk for developing breast cancer and a 15-65 percent lifetime risk for ovarian cancer. A study published in the journal The Lancet suggests that many women with a strong family history of these cancers would choose to undergo DNA testing to determine whether or not they have the BRCA1 or BRCA2 gene mutation.
Researchers in the Netherlands identified 682 people (411 women and 271 men) without cancer but who had a family history of breast or ovarian cancer and a 50 percent or 25 percent risk for carrying one of the gene mutations. Thirty-eight percent--48 percent of the women and 22 percent of the men--chose to undergo DNA testing to determine whether or not they carried a mutation. Women who were younger, who had children, and who had a high risk for a mutation were more likely to choose DNA testing.
Of the women who chose to have DNA testing, 44 percent of those with a 50 percent risk were found to have the mutation, and 15 percent of those with a 25 percent risk had the mutation. Of the men who chose testing, 44 percent with a 50 percent risk were found to be carriers.
Among the women who were found to have a mutation and who were eligible for surgery, 51 percent chose to undergo bilateral mastectomy (removal of all breast tissue). Sixty-four percent chose to undergo oophorectomy (removal of the ovaries). Women who had children were more likely to undergo mastectomy but not oophorectomy. Older women were more likely to have oophorectomy.
The study authors note that their findings may not translate well to other countries. They point out that, in the Netherlands, a predisposition for cancer does not affect an individual's health insurance or access to employment, which suggests that more people in their study may have chosen DNA testing than would in a country where these factors would be concerns. Furthermore, the cost of testing and of prophylactic surgery is covered by public and private health insurance. Finally, cultural differences may play a role in the perceived acceptability of DNA testing and prophylactic surgery.
Source: The Lancet. June 10, 2000. Volume 355, pp. 2015-2020
Body Fat Distribution, Weight Gain, and Breast Cancer Survival
Studies have found that women with an android (abdominal) body fat distribution and those who gain weight during adulthood have a higher risk for developing breast cancer. Now a study published in the journal Cancer suggests that these factors may influence breast cancer survival as well.
Researchers used a questionnaire to collect information about 166 women with breast cancer. The information included medical history, cancer diagnosis, medication use, and family history. They obtained body measurements for all subjects, including height, weight, and skin-fold measurements, and recorded the patients' weight histories at ages 16, 20, 30, and 40 years old. The patients were followed for at least ten years.
After ten years, 83 of the 166 breast cancer patients (50 percent) had died of the disease. They found that android body fat distribution at diagnosis was a statistically significant predictor of survival. Further, adult weight gain--which is predominantly android--as measured at age 30 was a significant predictor of survival. In fact, the study authors state that these two factors "are as important as predictors of survival as they are to risk" of breast cancer.
Other markers of general obesity, such as weight at diagnosis, body fat percentage, and body surface area were not related to breast cancer survival. Nor was height, skin-fold measurements, family history, or reproductive history.
The study authors point out that adult weight gain and android body fat distribution are risk factors that can be controlled in breast cancer patients to reduce their risk of recurrence or death. They suggest that further studies be carried out to examine the effect that reducing abdominal obesity in breast cancer patients has on their prognosis and survival.
Source: Cancer. June 15, 2000. Volume 88, No. 12, pp. 2751-2757
Breast-Conserving Therapy for Larger Tumors
Studies have shown that breast-conserving therapy (BCT)--removal of a cancerous tumor followed by additional treatment--is as effective as mastectomy (removal of the entire breast) for the treatment of small breast tumors. According to a report in the Journal of the National Cancer Institute, BCT may also be as effective as mastectomy for women with larger tumors.
A total of 868 women with breast cancer were randomly assigned to receive either BCT or mastectomy. BCT in this study consisted of lumpectomy (removal of a breast tumor and some surrounding tissue), removal of the lymph nodes in the underarm, radiation therapy, and sometimes chemotherapy. Eighty percent of the women's tumors were 2.1 to 5 centimeters (roughly 1 to 2 inches). Patients in the two groups were similar in age, menopausal status, and extent of disease.
After ten years, 65 percent of the BCT patients were alive and 66 percent of the mastectomy patients were alive. Further, 61 percent of the BCT patients had no evidence of cancer spread, while 66 percent of the mastectomy patients were free of cancer spread.
The rate of recurrence in the same breast (locoregional recurrence) differed between the groups, with 20 percent of the BCT patients having a locoregional recurrence and only 12 percent of the mastectomy patients having such a recurrence. The risk for recurrence in the BCT group was 1.64 times the risk in the mastectomy group. However, the higher risk for recurrence in the BCT patients did not cause a substantial difference in their rates of distant spread or overall survival.
Extent of lymph node involvement and tumor size appeared to be risk factors for locoregional recurrence, but the small number of patients with local recurrence in the study did not allow the researchers to analyze these risk factors. However, the authors suggest that these factors should be taken into account when deciding on treatment for breast cancer patients.
Source: Journal of the National Cancer Institute. July 19, 2000. Volume 92, No. 14, pp. 1143-1150
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