Steroid hormone receptor levels and adjuvant tamoxifen in early breast cancer. Ten year results of the Naples (GUN) Study

Estrogen receptor-positive, progesterone receptor-negative breast cancer: association with growth factor receptor expression and tamoxifen resistance

BACKGROUND

Clinical data indicate that estrogen receptor-positive/progesterone receptor-negative (ER+/PR-) breast cancers are less sensitive to tamoxifen than are ER+/PR+ tumors. It has also been reported that tamoxifen may be less effective in tumors that overexpress either HER-2 or HER-1 (epidermal growth factor receptor) and that signaling through these receptors reduces PR expression in experimental models. We hypothesized that ER+/PR- breast tumors are more likely than ER+/PR+ breast tumors to have an aggressive phenotype, to express HER-1 and overexpress HER-2, and are less likely to benefit from tamoxifen adjuvant therapy.

METHODS

Clinical and biological features of 31 415 patients with ER+/PR+ tumors were compared with those of 13,404 patients with ER+/PR- tumors. Association between disease-free survival (DFS) and HER-1 and HER-2 status was analyzed in a subset of 11,399 patients receiving adjuvant tamoxifen therapy. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox regression or Kaplan-Meier analyses, and all statistical tests were two-sided.

RESULTS

ER+/PR- tumors were more frequent in older patients, were larger in size, had a higher S-phase fraction, and were more likely to be aneuploid than ER+/PR+ tumors. Furthermore, three times as many ER+/PR- tumors as ER+/PR+ tumors expressed HER-1 (25% versus 8%; P < .001) and 50% more overexpressed HER-2 (21% versus 14%; P < .001). Among all tamoxifen-treated women, recurrence was higher among women with HER-1-expressing tumors than with HER-1-negative tumors (HR = 1.9, 95% CI = 1.0 to 3.5; P = .05); a stronger association between worse DFS and HER-2 overexpression was observed (HR = 2.3, 95% CI = 1.2 to 4.3; P = .006). However, results varied by PR status. Among tamoxifen-treated women with ER+/PR+ tumors, HER-1 or HER-2 status was not associated with worse DFS. Among women with ER+/PR- tumors, however, both HER-1 expression (HR = 2.4, 95% CI = 1.0 to 5.4; P = .036) and HER-2 overexpression (HR = 2.6, 95% CI = 1.1 to 6.0; P = .022) were associated with a higher likelihood of recurrence.

CONCLUSIONS

ER+/PR- tumors express higher levels of HER-1 and HER-2 and display more aggressive features than ER+/PR+ tumors. As in laboratory models, lack of PR expression in ER+ tumors may be a surrogate marker of aberrant growth factor signaling that could contribute to the tamoxifen resistance observed in these tumors.

The influence of tamoxifen treatment on the oestrogen receptor in metachronous contralateral breast cancer

Adjuvant tamoxifen treatment reduces the occurrence of contralateral breast cancer (CBC). The aim of the study was to investigate the hypothesis that adjuvant tamoxifen reduces the occurrence of oestrogen-receptor (ER)-positive CBC, but not the growth of ER-negative CBCs, and to examine survival after diagnosis of CBC. For the study, ER status was immunohistochemically assessed in CBCs of 35 tamoxifen-treated patients and 115 patients without previous hormonal treatment. Cases were retrieved from a series of patients treated from 1984 to 1995 at nine hospitals. The interval between ipsi- and contralateral breast cancer was at least 1 year. It was seen that the proportion of patients with an ER-negative CBC was significantly higher among those with prior tamoxifen treatment: 37% vs 18% (P=0.047). No difference between the two groups in overall and disease-specific survival following CBC was found. However, the stage differed for both groups: tamoxifen users more often had node-positive contralateral disease (P= 0.045). In conclusion, metachronous CBCs developing after 1-3 years of tamoxifen treatment are more often ER-negative breast cancers. So far this does not seem to have a major impact on survival.

CMF vs alternating CMF/EV in the adjuvant treatment of operable breast cancer. A single centre randomised clinical trial (Naples GUN-3 study)

The aim of this study was to test the hypothesis of Goldie and Coldman that the use of non-cross-resistant regimens of chemotherapy could lead to maximal anti-tumour effect. We compared standard CMF (cyclophosphamide, methotrexate, fluorouracil) with alternating CMF/EV (epirubicin, vincristine) in the adjuvant therapy of early breast cancer. Stage II premenopausal node-positive or post-menopausal node-positive oestrogen receptor-negative and stage III breast cancer patients were eligible for the study. From January 1985 to December 1990, 220 patients were randomised (115 to CMF and 105 to CMF/EV). Toxicity was mild; neurotoxicity, vomiting and hair loss were more frequent in the CMF/EV group, while permanent amenorrhoea, diarrhoea, stomach ache and minor infections occurred more often in the CMF arm. At a follow-up of 48 months, 113 patients (51.4%) had had recurrence (62 on CMF and 51 on CMF/EV) and 54 (24.5%) had died (30 on CMF and 24 on CMF/EV). There was no significant difference in disease-free and overall survival between the two arms. After adjusting for menopausal status and stage, the relative risk (RR) of recurrence for CMF/EV patients was 0.93 (95% CL 0.64-1.35), while the RR of death was 0.85 (95% CL 0.49-1.47). In conclusion, the Goldie-Coldman model of alternating therapy is not confirmed in this trial of adjuvant therapy of early breast cancer, although in view of its design a difference of less than 20% in 3 year disease-free survival could not be excluded.

Progesterone receptor determined by immunocytochemical and biochemical methods in human breast cancer

Immunocytochemical assay (ICA) of the progesterone receptor (PgR) was performed on 152 patients with stage I-II breast cancer. We employed the rat monoclonal antibody KD-68 and a peroxidase/antiperoxidase displaying system. The results obtained by ICA (Pg(RICA)) were compared with those by the biochemical dextran-coated charcoal assay (PgRDCC). Comparing the two methods we found an overall agreement (accuracy) of 77.5%, a PgR(ICA) sensitivity of 83.5% and a specificity of 73%. Both methods were significantly associated with oestrogen receptor expression, detected by DCC (P less than 0.001 for PgRDCC and P = 0.0014 for PgR(ICA)). No significant association was found between PgR(ICA) or PgRDCC and the other clinicopathological features analysed. After a median follow-up of 36 months, the overall survival probability was 91% in PgRDCC-positive versus 81.5% in PgRDCC-negative patients (log-rank test, chi 2 = 0.91) compared to 87.5% in PgR(ICA)-positive versus 82% in PgR(ICA)-negative ones (log-rank test, chi 2 = 0.93). Disease-free survival probability was 74.5% in both PgRDCC-positive and PgRDCC-negative patients (log-rank test, chi 2 = 0.02) compared to 78% in PgR(ICA)-positive versus 71.5% in PgR(ICA)-negative cases (log-rank test, chi 2 = 0.37). The present study demonstrates that ICA is a reliable method to detect PgR, correlating well with the DCC assay. Moreover, the ICA assay seems to provide clinical information complementary to the biochemical method. The definition of its prognostic value in operable breast cancer needs additional studies, particularly in node-negative patients.