Research Review

 

Accuracy of Biopsy Methods for Diagnosis of Breast Cancer

Ultrasound-guided fine-needle aspiration biopsy (US-FNAB) is commonly used for the diagnosis of breast tumors. In this procedure, a very fine needle is inserted into a breast lump with the help of ultrasound imaging. A sample is collected via the needle and analyzed in the laboratory.

A recent study published in the Journal of the American College of Surgeons compares the effectiveness of US-FNAB with that of a similar procedure: ultrasound-guided core needle biopsy (US-CNB). The latter procedure uses a larger needle and enables removal of a larger tissue sample for analysis. US-FNAB was performed in 233 patients with unidentified breast lumps; in 81 of these patients, US-CNB was also performed. The diagnoses obtained with these procedures were compared with surgical findings.

The accuracy of US-FNAB was found to be 84%, while the accuracy of US-CNB was 89%. When results of both biopsies were taken together, accuracy was 100%. US-CNB distinguished benign from malignant tumors with greater accuracy and less often yielded an inadequate sample for analysis. CNB also yielded no false-positive results (diagnosis of cancer in a tumor that is actually benign).

Source: Journal of the American College of Surgeons. Volume 190, pp. 299-303

Breast Cancer Risk and Contraceptive Use

Some recent research has shown an association between oral contraceptive use and an increased risk of breast cancer for women under age 35 and those who have used oral contraceptives recently. A new study published in the American Journal of Epidemiology found no increased risk among women using injectable progestogen (Depo-Provera) and a slight increased risk among those using combined estrogen/progestogen oral contraceptives.

Data for 494 women with invasive breast cancer and 1,625 women without breast cancer were analyzed for the study, conducted in South Africa. The women in the control group were matched to the breast cancer cases for decade of age, ethnic group, and area of residence. The women, all of whom were black or of mixed racial descent, were interviewed between 1994 and 1997 regarding their contraceptive use.

Sixty-six percent of the women with breast cancer and 71 percent of the control women had used injectable progestogen. Researchers found no increased risk for breast cancer among the users, even when the data were analyzed by age, recency of use, and duration of use.

Combined estrogen/progestogen oral contraceptives were used by 45 percent of the women with breast cancer and 39 percent of the control women. There was an overall 1.2-fold increase in breast cancer risk for these women, a risk the authors labeled "of borderline significance." For women under age 35, there was a 1.7-fold increase. The risk did not change with duration of use or time since first or last use.

The study authors note that bias could have been a factor in the increased risk observed among younger oral contraceptive users. They state: "Information bias could have occurred if the cases reported their contraceptive exposures more fully than the controls. For COC [combined oral contraceptive] users, it is possible that greater awareness of the hypothesis among women below age 35 years may have contributed to the observed association."

Source: American Journal of Epidemiology. Volume 151, No. 4, pp. 396-403

Chemotherapy Before Surgery for Some Breast Tumors

Chemotherapy administered before surgery (induction chemotherapy) may allow more breast cancer patients to forgo mastectomy in favor of less invasive surgical procedures.

In a study published in the journal Cancer, 129 patients with stage IIa, IIb, or IIIa breast cancer completed 3-5 cycles of induction chemotherapy with one of two chemotherapy regimens (paclitaxel or FAC: fluorouracil, doxorubicin, and cyclophosphamide). They did not receive radiation therapy but did undergo removal of some axillary (armpit) lymph nodes. After induction chemotherapy, the patients had segmental mastectomy or modified radical mastectomy followed by 4 additional cycles of chemotherapy.

Before induction chemotherapy, the median tumor size in the group was 4 centimeters; after the chemotherapy, the median was 1.6 centimeters. Thirty-six percent of the patients had a partial tumor response to the chemotherapy, and 24% of the patients had no evidence of tumor after the chemotherapy. The response was similar with the two chemotherapy regimens. None of the patients had progression of disease after chemotherapy.

Thirty-four percent of the patients who had positive lymph nodes before the chemotherapy had no evidence of lymph node involvement after the treatment. Another 38% had only 1-3 remaining positive lymph nodes.

The ability of induction chemotherapy to shrink tumor size and reduce lymph node involvement may allow more women with stage IIa, IIb, and IIIa disease to have breast-conserving surgery.

Source: Cancer. March 15, 2000. Volume 88, No. 6, pp. 1417-1424

Diet and Mammographic Breast Density

Studies have shown that the density of breast tissue as seen on mammograms is a risk factor for breast cancer. A new study adds to previous knowledge about the effect that diet has on breast density.

A total of 1,508 women participated in the study. Interviews were conducted to gather information about the participants' medical histories and lifestyle, and the participants completed a food frequency questionnaire. A recent mammogram of each participant was analyzed to estimate breast density. Women with a history of breast cancer were not included in the study, because the diagnosis may have led these women to change their diets.

No association was found between breast density and intake of total fat, total calories, or cholesterol. Increased breast density was seen in premenopausal women with higher intakes of polyunsaturated fat and vitamins C and E, while decreased breast density was evident with increased intake of saturated fat and total dairy intake. Among postmenopausal women, higher vitamin B12 intake was associated with increased breast density. The associations noted for vitamin C and vitamin B12 were seen only in women taking supplements.

The study authors conclude: "The cross-sectional differences in breast density across levels of dietary factors were small in magnitude but may have implications for breast cancer risk."

Source: Cancer Epidemiology, Biomarkers & Prevention. February 2000. Volume 9, pp. 151-160

Left-Handed Women and Breast Cancer Risk

A recent study published in the journal Epidemiology found that left-handed women may have an increased risk for breast cancer. Researchers analyzed data for 4,230 postmenopausal women: 1,837 women aged 50-79 with a first diagnosis of invasive breast cancer and 2,393 randomly selected controls who were matched for age to the case women. They discovered that left-handed women had a 42 percent higher risk for developing breast cancer than right-handed women. Ambidextrous women--those who did not claim a hand preference--had a 26 percent higher risk than right-handed women.

The breast cancer risk associated with left-handedness increased with age, with women in the oldest age group (70-79) having a twofold greater risk than women in the youngest age group (50-59). The authors speculate that this difference may be related to the fact that left-handed children were encouraged to convert to right-handedness several decades ago when the oldest women studied were young. The older women in the study claiming left-handedness may be the ones who did not switch to right-handedness despite pressure to do so. "These women may have a stronger predisposition to left-handedness, perhaps reflecting causes of left-handedness that are associated with breast cancer risk, including intrauterine hormonal milieu, or genetic predisposition," write the authors.

Left-handedness was examined in this study because it appears to indicate intrauterine (in the womb) exposure to steroid hormones. Breast cancer risk may be associated with this hormone exposure.

Source: Epidemiology. March 2000. Volume 11, No. 2, pp. 181-184

Exposure to Gasoline and Increased Risk for Male Breast Cancer

A Danish study reports an association between male breast cancer risk and exposure to gasoline and its combustion products. The findings were published in the American Journal of Industrial Medicine.

Researchers looked at data for 230 men diagnosed with breast cancer from 1970-1989. Each patient with breast cancer was age-matched with 56 randomly selected male control subjects for statistical purposes.

Men who were employed for at least three months in industries with known exposure to gasoline vapors and combustion products were found to have a significantly increased risk for breast cancer compared with men in other industries. The risk increased when the researchers allowed for a ten-year period between first employment exposure and the date of diagnosis.

Breast cancer risk was highest among men under 40 years old and among those whose first exposure occurred before 1965. The authors suggest that the younger men may have had higher sensitivity to the exposure, and those whose exposure occurred before 1965 may have worked with higher concentrations of pollutants.

Source: American Journal of Industrial Medicine. Volume 37, pp. 349-352

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