Management and outcome of HER2-positive early breast cancer treated with or without trastuzumab in the adjuvant trastuzumab era.

ABSTRACT

BACKGROUND: Adjuvant trastuzumab (AT) is known to significantly improve survival of women with HER2(+) early breast cancer. This study explores the use and nonuse of AT in early breast cancer, as well as the efficacy in a neoadjuvant and adjuvant population, within a routine clinical setting. PATIENTS AND METHODS: Histopathology reports of invasive breast cancer resected at Imperial College Healthcare NHS Trust (ICHT) between January 2006 and December 2008 were reviewed. HER2(+) patients were identified and their case notes reviewed. In addition, patients who received AT at our center but underwent surgery elsewhere were included in the efficacy and safety analyses. RESULTS: The local HER2(+) rate was 13.1%, with 54.5% of these patients receiving AT. A total of 128 patients received AT (85 local and 43 referrals from elsewhere). Neoadjuvant chemotherapy (CT) followed by postoperative AT was associated with a significantly increased risk of recurrence compared with adjuvant CT and then AT (hazard ratio [HR] 18.6 [95% CI, 1.8-152.2]; P = .013). The proportion of patients who were disease free at 3 years from primary therapy was 96.4% (95% CI, 89.8%-100%) for adjuvant therapy, compared with 72.0% (95% CI, 56.5%-91.6%) for neoadjuvant therapy. AT was omitted in 49 HER2(+) patients; the main reason for AT omission was clinical judgment that the breast cancer was low risk. Patients treated with AT had a significantly decreased risk of recurrence (HR 0.27 [95% CI, 0.08-0.97]; P = .04) compared with the untreated patients. The majority of untreated relapses were in patients in whom there was an original intent to use AT. The proportion alive at 3 years for adjuvant CT, neoadjuvant CT, and untreated AT was 100%, 74.5%, and 92.7% respectively. CONCLUSION: The overall efficacy and safety of AT in our routine clinical setting is comparable to the large randomized trials. HER2(+) patients who underwent neoadjuvant CT had a significantly increased risk of disease recurrence compared with patients treated with adjuvant CT followed by trastuzumab. Untreated patients had an increased risk of recurrence.