Selection of primary breast cancer patients for adjuvant endocrine therapy--is oestrogen receptor alone adequate?

The effects of gefitinib in tamoxifen-resistant and hormone-insensitive breast cancer: a phase II study

Estrogen receptor (ER)-positive acquired tamoxifen-resistant (TAM-R) MCF-7 breast cancer cell lines exhibit epidermal growth factor receptor (EGFR) expression/signaling and are growth-inhibited by gefitinib (IRESSA). We examined the effect of gefitinib on ER-positive TAM-R and ER-negative hormone-insensitive breast cancer in a Phase II study. Fifty-four patients with breast cancer [ER-positive/acquired TAM-R (n = 28); ER-negative (n = 26)] received oral gefitinib 500 mg/day. Tumor biopsies were taken pre- (n = 28) and 8 weeks post-treatment (n = 14 matched samples). Gefitinib was well tolerated and the clinical benefit rate (objective response or stable disease >24 weeks) was 33.3% overall (n = 18/54), and 53.6 and 11.5% in ER-positive/TAM-R and ER-negative patients, respectively. Pretreatment ER and progesterone receptor-positivity were associated with response (p < 0.001 and 0.016, respectively) and longer progression-free survival (PFS; p= 0.001 and 0.013, respectively). All patients expressed EGFR, but high pretreatment levels predicted poorer outcome (p = 0.005) and shorter PFS (p = 0.012) with gefitinib. In patients with clinical benefit, reduced Ki67 staining during treatment (p = 0.024) was commonly observed, and those with >10% decline in EGFR phosphorylation demonstrated parallel decreases in ERK1/2 MAPK phosphorylation. Acquired tamoxifen resistance appears in part mediated through EGFR signaling and can be blocked with gefitinib.

Growth factor signalling in endocrine and anti-growth factor resistant breast cancer

Growth factors provide powerful mitogenic and survival signals to breast cancer cells and it is therefore not surprising that they are able to subvert inhibitory responses to anti-hormonal drugs. In this review we discuss several mechanisms by which this may be achieved and expand our observations to encompass recently emerging anti-growth factor treatments. The information presented is underpinned by inhibitor studies that show the targeting of such mechanisms in advance of anti-hormone or anti-growth factor resistance development is able to substantially delay this event, thus pointing the way forward to intelligent combination therapies relevant to the future management of breast cancer.

Endocrine therapy for breast cancer: an overview

Endocrine therapy for breast cancer has been established in the adjuvant treatment for primary disease and in the treatment of advanced disease. The ER remains the best predictor of response although other factors exist and need to be identified. Pharmacological manipulation has been replacing ablative procedures. Tamoxifen used to be the most popular agent of choice and promising new agents include the pure anti-oestrogens and the third generation selective aromatase inhibitors. Ongoing and future studies will optimise treatment in established areas and will exploit its potential roles in preoperative use and chemoprevention.

Heterogeneic expression of estrogen receptor between the primary tumor and the corresponding involved lymph nodes in patients with node-positive breast cancer and its implications in patient outcome

BACKGROUND AND OBJECTIVES

The estrogen-receptor (ER) status of breast cancers has typically been evaluated in primary tumors (PTs), and the influence of ER expression in the involved lymph nodes (LNs) on prognosis of the patients with node-positive breast cancer remains unclear. The expression of ER was compared between PT and corresponding involved LNs in patients with node-positive breast cancer.

METHODS

Eighty-seven patients with node-positive breast cancer were immunohistochemically assessed to measure the expression of ER in PT and involved LN with anti-ER monoclonal antibody.

RESULTS

Thirty-five (40.2%) of PTs and 26 (29.9%) of involved LNs were evaluated as ER(+). The ER expression in PTs was significantly correlated with that in involved LNs (P < 0.0001), and the ER expression was almost the same in both the PT and corresponding involved LN in 66 cases (75.9%): both (+), 20 (23.0%); and both (-), 46 (52.9%). However, ER expression differed in 21 cases (24.1%) between involved LN and the corresponding PT: PT-ER(+)/LN-ER(-), 15 (17.2%); and PT-ER(-)/LN-ER(+), 6 (6.9%). The survival of patients with ER(+)-PT was significantly better than that of ER(-)-PT patients (P = 0.0086), but ER expression in involved LN did not have any significant effect on patient survival. Furthermore, when survival periods were grouped by coexpression of ER in the PT and involved LN, the best survival was seen in the PT-ER(+)/LN-ER(-) group (P < 0.001 vs. others). In the patients, who received adjuvant endocrine therapy, the survival of the PT-ER(+) group was significantly better than that of PT-ER(-) group (P = 0.0145), but LN-ER expression did not show any significant influence on the survival rate. Multivariate analysis demonstrated that clinical stage and ER-expression in the PT were significant variables, but ER expression in the involved LN was not.

CONCLUSIONS

The ER expression was discordant between PT and involved LN in about 24% of the breast cancers evaluated, and ER expression in involved LNs had less influence on patient prognosis than ER expression in the corresponding PT.