Carol Redmond

BACKGROUND: The finding of a decrease in contralateral breast cancer incidence following tamoxifen administration for adjuvant therapy led to the concept that the drug might play a role in breast cancer prevention. To test this hypothesis, the National Surgical Adjuvant Breast and Bowel Project initiated the Breast Cancer Prevention Trial (P-1) in 1992. METHODS: Women (N=13388) at increased risk for breast cancer because they 1) were 60 years of age or older, 2) were 35-59 years of age with a 5-year predicted risk for breast cancer of at least 1.66%, or 3) had a history of lobular carcinoma in situ were randomly assigned to receive placebo (n=6707) or 20 mg/day tamoxifen (n=6681) for 5 years. Gail's algorithm, based on a multivariate logistic regression model using combinations of risk factors, was used to estimate the probability (risk) of occurrence of breast cancer over time. RESULTS: Tamoxifen reduced the risk of invasive breast cancer by 49% (two-sided P<.00001), with cumulative incidence through 69 months of follow-up of 43.4 versus 22.0 per 1000 women in the placebo and tamoxifen groups, respectively. The decreased risk occurred in women aged 49 years or younger (44%), 50-59 years (51%), and 60 years or older (55%); risk was also reduced in women with a history of lobular carcinoma in situ (56%) or atypical hyperplasia (86%) and in those with any category of predicted 5-year risk. Tamoxifen reduced the risk of noninvasive breast cancer by 50% (two-sided P<.002). Tamoxifen reduced the occurrence of estrogen receptor-positive tumors by 69%, but no difference in the occurrence of estrogen receptor-negative tumors was seen. Tamoxifen administration did not alter the average annual rate of ischemic heart disease; however, a reduction in hip, radius (Colles'), and spine fractures was observed. The rate of endometrial cancer was increased in the tamoxifen group (risk ratio = 2.53; 95% confidence interval = 1.35-4.97); this increased risk occurred predominantly in women aged 50 years or older. All endometrial cancers in the tamoxifen group were stage I (localized disease); no endometrial cancer deaths have occurred in this group. No liver cancers or increase in colon, rectal, ovarian, or other tumors was observed in the tamoxifen group. The rates of stroke, pulmonary embolism, and deep-vein thrombosis were elevated in the tamoxifen group; these events occurred more frequently in women aged 50 years or older. CONCLUSIONS: Tamoxifen decreases the incidence of invasive and noninvasive breast cancer. Despite side effects resulting from administration of tamoxifen, its use as a breast cancer preventive agent is appropriate in many women at increased risk for the disease.

In 1976 we began a randomized trial to evaluate breast conservation by a segmental mastectomy in the treatment of Stage I and II breast tumors less than or equal to 4 cm in size. The operation removes only sufficient tissue to ensure that margins of resected specimens are free of tumor. Women were randomly assigned to total mastectomy, segmental mastectomy alone, or segmental mastectomy followed by breast irradiation. All patients had axillary dissections, and patients with positive nodes received chemotherapy. Life-table estimates based on data from 1843 women indicated that treatment by segmental mastectomy, with or without breast irradiation, resulted in disease-free, distant-disease-free, and overall survival at five years that was no worse than that after total breast removal. In fact, disease-free survival after segmental mastectomy plus radiation was better than disease-free survival after total mastectomy (P = 0.04), and overall survival after segmental mastectomy, with or without radiation, was better than overall survival after total mastectomy (P = 0.07, and 0.06, respectively). A total of 92.3 per cent of women treated with radiation remained free of breast tumor at five years, as compared with 72.1 per cent of those receiving no radiation (P less than 0.001). Among patients with positive nodes 97.9 per cent of women treated with radiation and 63.8 per cent of those receiving no radiation remained tumor-free (P less than 0.001), although both groups received chemotherapy. We conclude that segmental mastectomy, followed by breast irradiation in all patients and adjuvant chemotherapy in women with positive nodes, is appropriate therapy for Stage I and II breast tumors less than or equal to 4 cm, provided that margins of resected specimens are free of tumor.

In 1985 we presented results of a randomized trial involving 1843 women followed for five years that indicated that segmental breast resection (lumpectomy) followed by breast irradiation is appropriate therapy for patients with Stage I or II breast cancer (tumor size, less than or equal to 4 cm), provided that the margins of the resected specimens are free of tumor. Women with positive axillary nodes received adjuvant chemotherapy. Lumpectomy followed by irradiation resulted in a five-year survival rate of 85 percent, as compared with 76 percent for total mastectomy, a rate of survival free of distant disease of 76 percent, as compared with 72 percent, and a disease-free survival rate of 72 percent, as compared with 66 percent. In the current study, we have extended our observations through eight years of follow-up. Ninety percent of the women treated with breast irradiation after lumpectomy remained free of ipsilateral breast tumor, as compared with 61 percent of those not treated with irradiation after lumpectomy (P less than 0.001). Among patients with positive axillary nodes, only 6 percent of those treated with radiation and adjuvant chemotherapy had a recurrence of tumor in the ipsilateral breast. Lumpectomy with or without irradiation of the breast resulted in rates of disease-free survival (58 +/- 2.6 percent), distant-disease-free survival (65 +/- 2.6 percent), and overall survival (71 +/- 2.6 percent) that were not significantly different from those observed after total mastectomy (54 +/- 2.4 percent, 62 +/- 2.3 percent, and 71 +/- 2.4 percent, respectively). There was no significant difference in the rates of distant-disease-free survival (P = 0.2) or survival (P = 0.3) among the women who underwent lumpectomy (with or without irradiation), despite the greater incidence of recurrence of tumor in the ipsilateral breast in those who received no radiation. We conclude that our observations through eight years are consistent with the findings at five years and that these new findings continue to support the use of lumpectomy in patients with Stage I or II breast cancer. We also conclude that irradiation reduces the probability of local recurrence of tumor in patients treated with lumpectomy.

We conducted a randomized, double-blind, placebo-controlled trial of postoperative therapy with tamoxifen (10 mg twice a day) in 2644 patients with breast cancer, histologically negative axillary nodes, and estrogen-receptor-positive (greater than or equal to 10 fmol) tumors. No survival advantage was observed during four years of follow-up (92 percent for placebo vs. 93 percent for tamoxifen; P = 0.3). There was a significant prolongation of disease-free survival among women treated with tamoxifen, as compared with those receiving placebo (83 percent vs. 77 percent; P less than 0.00001). This advantage was observed in both the patients less than or equal to 49 years old (P = 0.0005) and those greater than or equal to 50 (P = 0.0008), particularly in the former, among whom the rate of treatment failure was reduced by 44 percent. Multivariate analysis indicated that all subgroups of patients benefited. Tamoxifen significantly reduced the rate of treatment failure at local and distant sites, tumors in the opposite breast, and the incidence of tumor recurrence after lumpectomy and breast irradiation. The benefit was attained with a low incidence of clinically appreciable toxic effects. The magnitude of the improvement obtained does not preclude the need for future trials in which patients given tamoxifen could serve as the control group in an evaluation of potentially better therapies. Tamoxifen treatment is justified in patients who meet the eligibility criteria of the present study and who refuse to participate in those trials. Since patients with tumors too small for conventional analysis of estrogen-receptor and progesterone-receptor concentrations were not eligible for this study, no information is available to indicate that such patients should receive tamoxifen.

BACKGROUND: Previous findings from a clinical trial (Protocol B-06) conducted by the National Surgical Adjuvant Breast and Bowel Project (NSABP) indicated the worth of lumpectomy and breast irradiation for treating breast cancer. After the discovery by NSABP staff members of falsified information on patients enrolled in the study by St. Luc Hospital in Montreal, separate audits were conducted at St. Luc Hospital and other participating institutions. We report the results of both audits and update the study findings through an average of 12 years of follow-up. METHODS: Patients with either negative or positive axillary nodes and tumors 4 cm or less in diameter were randomly assigned to one of three treatments: total mastectomy, lumpectomy followed by breast irradiation, or lumpectomy without irradiation. Three cohorts of patients were analyzed. The first cohort included all 2105 randomized patients, who were analyzed according to the intention-to-treat principle. The second cohort consisted of 1851 eligible patients in the first cohort with known nodal status who agreed to be followed and who accepted their assigned therapy (among those excluded were 6 patients from St. Luc Hospital who were declared ineligible because of falsified biopsy dates). The third cohort consisted of the patients in the second cohort minus the 322 eligible patients from St. Luc Hospital (total, 1529 patients). RESULTS: Regardless of the cohort, no significant differences were found in overall survival, disease-free survival, or survival free of disease at distant sites between the patients who underwent total mastectomy and those treated by lumpectomy alone or by lumpectomy plus breast irradiation. After 12 years of follow-up, the cumulative incidence of a recurrence of tumor in the ipsilateral breast was 35 percent in the group treated with lumpectomy alone and 10 percent in the group treated with lumpectomy and breast irradiation (P < 0.001). CONCLUSIONS: Our findings continue to indicate that lumpectomy followed by breast irradiation is appropriate therapy for women with either negative or positive axillary nodes and breast tumors 4 cm or less in diameter.