Relative worth of estrogen or progesterone receptor and pathologic characteristics of differentiation as indicators of prognosis in node negative breast cancer patients: findings from National Surgical Adjuvant Breast and Bowel Project Protocol B-06.
This study correlates the disease-free survival (DFS), distant disease-free survival (DDFS), and survival (S) of 1,157 histologically node negative breast cancer patients with the estrogen and/or progesterone receptor (ER, PR) and with the nuclear or histologic grade (NG, HG) of their tumors. All were treated by operation without systemic adjuvant therapy. The DFS, DDFS, and S were significantly greater (P = .005, .004, less than .001) in patients with ER positive than ER negative tumors but the magnitude of the differences after 5 years of follow-up was slight (8% in both DFS and DDFS and 10% in S). Differences of that magnitude are insufficient to discriminate clearly between patients who should or should not receive systemic therapy. As with ER, there were outcome differences in favor of PR positive tumors but only in S was the difference significant (8% at 5 years; P = .002). When combined with ER, PR made no independent contribution in the outcome prediction. Regression analysis indicated that NG was the most important single marker of outcome. The prognosis of women with unknown ER or PR was equivalent to or better than that in those with ER or PR positive tumors. This finding seems to be related to tumor size in that a higher proportion of tumors with unknown receptors were less than 1.0 cm, thus having insufficient tissue for analysis. Our findings disclose that in node negative breast cancer patients, NG is a better marker of prognosis than is tumor ER, and that PR is of little or no value. Tumor NG may also be useful for selecting the type of systemic therapy to be used in these patients.