Should adjuvant trastuzumab be offered in very early-stage (pT1a/bN0M0) HER2-neu-positive breast cancer? A current debate

The Role of Trastuzumab in Patients with HER2 Positive Small (pT1mi/a) Breast Cancers, a Multicenter Retrospective Study

Simple Summary

Treatment of small HER2+ breast cancers with adjuvant Trastuzumab is still controversial. This study aims to measure the effect of Trastuzumab in early stages of breast cancer (pT1mic/a pN0/1mi) in terms of disease recurrence and to identify which factors most affect the prognosis of small HER2+ tumors. We retrospectively selected and reviewed 100 HER2+ pT1mic-pT1a breast cancer patients with a median follow-up of 86 months. In our study the primary outcome was the disease recurrence rate, which appeared to be significantly lower among patients who received adjuvant Trastuzumab. Among the patients who did not receive adjuvant Trastuzumab, HR− HER2+ tumors showed a risk seven times higher of relapse. The results of our study indicate that adjuvant Trastuzumab reduces the risk of developing a disease recurrence even in small HER2+ tumors. Adjuvant targeted therapy should be considered in patients with HR− HER2+ tumors, the category with the highest risk of recurrence.

Abstract

The treatment with adjuvant Trastuzumab in patients diagnosed with HER2+ small breast cancers is controversial: limited prospective data from randomized trials is available. This study aims to measure the effect of Trastuzumab in the early stages of breast cancer (pT1mic/a pN0/1mi) in terms of disease recurrence and to identify which are the factors that most affect the prognosis of small HER2+ tumors. One hundred HER2+ pT1mic-pT1a breast cancer patients who were treated in three Turin Breast Units between January 1998 and December 2018 were retrospectively selected and reviewed. Trastuzumab was administered to 23 patients. Clinicopathological features and disease-free survival (DFS) were compared between different subgroups. The primary outcome was the disease recurrence rate. Median follow-up time was 86 months. Compared to pT1a tumors, pT1mic lesions had a higher tumor grade (84% of pT1mic vs. 55% of pT1a; p = 0.003), a higher Ki-67 index (81% vs. 46%; p = 0.007) and were more frequently hormone receptor (HR) negative (69% vs. 36%, p = 0.001). Disease recurrence rate was significantly lower among patients who received adjuvant Trastuzumab (p = 0.02), with this therapy conferring an 85% reduction in the risk of relapse (HR 0.15; p = 0.02). Among the patients who did not receive adjuvant Trastuzumab, the only factor significantly associated with an increased risk of developing a recurrence was the immunohistochemical (IHC) subtype: in fact, HR− HER2+ tumors showed a risk seven times higher of relapsing (HR 7.29; p = 0.003). Adjuvant Trastuzumab appears to reduce the risk of disease recurrence even in small HER2+ tumors. The adjuvant targeted therapy should be considered in patients with HR− HER2+ tumors since they have the highest risk of recurrence, independently from size and grade.

Systemic targeted therapy for her2-positive early female breast cancer: a systematic review of the evidence for the 2014 Cancer Care Ontario systemic therapy guideline

BACKGROUND

This systematic review addresses the question "What is the optimal targeted therapy for female patients with early-stage human epidermal growth factor receptor 2 (her2)-positive breast cancer?"

METHODS

The medline and embase databases were searched for the period January 2008 to May 2014. The Standards and Guidelines Evidence directory of cancer guidelines and the Web sites of major guideline organizations were also searched.

RESULTS

Sixty publications relevant to the targeted therapy portion of the systematic review were identified. In four major trials (hera, National Surgical Adjuvant Breast and Bowel Project B-31, North Central Cancer Treatment Group N9831, and Breast Cancer International Research Group 006), adjuvant trastuzumab for 1 year was superior in disease-free survival (dfs) and overall survival (os) to no trastuzumab; trastuzumab showed no benefit in one trial (pacs 04). A shorter duration of trastuzumab (less than 1 year compared with 1 year) was evaluated, with mixed results for dfs: one trial showed superiority (finher), one trial could not demonstrate noninferiority (phare), another trial showed equivalent results (E 2198), and one trial is still ongoing (persephone). Longer trastuzumab duration (hera: 2 years vs. 1 year) showed no improvement in dfs or os and a higher rate of cardiac events. Newer her2-targeted agents (lapatinib, pertuzumab, T-DM1, neratinib) have been or are still being evaluated in both adjuvant and neoadjuvant trials, either by direct comparison with trastuzumab alone or combined with trastuzumab. In the neoadjuvant setting (neoaltto, GeparQuinto, Neosphere), trastuzumab alone or in combination with another anti-her2 agent (lapatinib, pertuzumab) was compared with either lapatinib or pertuzumab alone and showed superior or equivalent rates of pathologic complete response. In the adjuvant setting, lapatinib alone or in combination with trastuzumab, compared with trastuzumab alone (altto) or with placebo (teach), was not superior in dfs. The results of the completed aphinity trial, evaluating the role of dual her2 blockade with trastuzumab and pertuzumab, are highly anticipated. Ongoing trials are evaluating trastuzumab as a single agent without adjuvant chemotherapy (respect) and in patients with low her2 expression (National Surgical Adjuvant Breast and Bowel Project B-47).

CONCLUSIONS

Taking into consideration disease characteristics and patient preference, 1 year of trastuzumab should be offered to all patients with her2-positive breast cancer who are receiving adjuvant chemotherapy. Cardiac function should be regularly assessed in this patient population.