Infiltrating breast carcinoma smaller than 0.5 centimeters

Abstract

Saiz et al.1 pose an interesting question regarding the management of small invasive breast carcinomas; this is especially relevant with the more frequent detection of small tumors due to breast screening by mammography and the promise of future three-dimensional breast screening modalities.2 Saiz et al. performed careful assessment of banked pathologic materials for 117 tumors that measured ≤ 1.0 cm, 24 of which measured ≤ 0.5 cm; the workup included an attribution for the size of multiple foci through the summation of maximum dimensions of invasive tumor. The conclusion was that it might not be necessary for patients with T1a tumors to undergo axillary lymph node (LN) dissection because there were no observed LN metastases for this group of patients. Women's College Hospital of the University of Toronto has used mammography routinely for more than 30 years. In a full cohort of primary invasive breast carcinoma patients accrued between 1971–1990 and followed until 1996,3 we attributed tumor sizes by the standard maximum dimension (for the largest focus, when the disease was multifocal), the sum of the greatest dimensions (as in the article by Saiz et al.1), and the surface area or volume (for all foci). We reported that there were 112 patients with tumors measuring ≤ 1 cm by the standard maximum dimension and 108 patients with tumors equivalent to ≤ 1 cm tumors by summed tumor size/surface area/volume. The article by Saiz et al.1 prompted us to reexamine our data, dividing the patients into those with T1a and T1b tumors; we report the results for standard (and summed) tumor sizes. The summed size is comparable to the article by Saiz et al. and in our patients was equivalent to surface area or volume for tumors measuring ≤ 1 cm. We found that patients with T1a and T1b tumors had similar LN involvement; 5 of 16 T1a patients (31%) were LN positive compared with 17 of 47 T1b patients (36%) (P = 0.72 by the Pearson chi-square test [respectively, by summed tumor dimensions, 5 of 16 (31%), 15 of 44 (34%); P = 0.84]). In addition, we compared survival from breast carcinoma for our T1a patients who were histologically LN negative, clinically LN negative (no axillary LN dissection performed), and LN positive, using a Wilcoxon (Peto-Prentice) test statistic. None of the 11 histologically LN negative patients, 2 of 17 of the clinically LN negative patients (12%), and 1 of 5 of the LN positive patients (20%) had died from breast carcinoma at last follow-up (P = 0.28). Saiz et al. provide an interesting literature review of LN status for T1a and T1b tumors in Table 1 of their article. Only 2 of 11 articles reported no LN involvement for T1a patients; including the article by Saiz et al., this would increase to 3 of 12 articles, or 25% of the articles in the reviewed literature. From these 12 studies, 178 of 1149 T1a patients (15%) were LN positive; a simple two-sided normal test of the hypothesis that T1a patients are expected to be LN negative is strongly rejected (P < 0.001). The 31% rate of LN involvement for our T1a patients marginally exceeded the highest report of 28% by Nemoto et al.4 The overall data undermine the conclusion reached by Saiz et al. that patients with T1a tumors generally might be spared an axillary LN dissection. Previous investigations with our full cohort of 678 patients with invasive breast carcinoma indicated that women age ≥ 65 years were more likely to die from another cause of death than those women age < 65 years.5 Furthermore, not performing an axillary LN dissection in elderly patients when they were clinically LN negative after a thorough clinical examination did not appear to have a detrimental effect on breast carcinoma mortality. Only 3 of the 90 clinically LN negative patients age ≥ 65 years had tumors measuring ≤ 0.5 cm. The article by Saiz et al.1 raises the question of appropriate therapeutic modalities for small invasive breast carcinoma that we anticipate will become an increasingly important issue to address. Some elderly patients who clinically are LN negative after a thorough examination, and who possibly have other major concomitant health problems, might be candidates for close follow-up with potentially delayed axillary LN dissection; however, caution is needed in patients age < 65 years because our experience5 has shown that the majority of deaths in these women were from breast carcinoma. Judith-Anne W. Chapman Ph.D.*, Richard Gordon Ph.D. , Marilyn A. Link*, Edward B. Fish M.D.*, * Henrietta Banting Breast Centre, Women's College Hospital, University of Toronto, Toronto, Ontario, Canada, Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada