The effects of not receiving appropriate breast cancer treatment

The authors aimed to determine the recurrence (the cancer returns) rates in women with human epidermal growth factor receptor 2 positive (HER2+) breast cancer who do not receive anti-HER2+ therapy.

HER2+ breast cancer is a specific sub-type of breast cancer dependent on the HER2 protein for growth. It is often targeted with a particular anti-HER2 therapy drug called trastuzumab (Herceptin). This drug targets the HER2 receptor and blocks the tumor's ability to grow.

Due to economic limitations worldwide, many women with this cancer sub-type do not receive the specified drug treatment. The risk of cancer recurrence within these women due to lack of appropriate treatments have not been fully understood.

The aim of this study was to determine the rates of cancer recurrence among women with HER2+ breast cancer, specifically those who did not receive anti-HER2+ therapy.

A total of 1260 women with HER2+ breast cancer not treated with anti-HER2 therapy were included in the study. 55% of these patients also showed positivity for hormone receptors (HR+, dependent on the hormones estrogen and/or progesteron for growth), with 45% HR negative (HR-).

Overall, disease-free survival (time from treatment until disease recurs) was 75% after 5 years and 61% after 10. The risk of recurrence decreases from 10% in the first year to 3.5% after 5 years.

The HR status of the tumor served as a prognostic factor (predicts outcome). Those with HR+ status had a reduced risk of recurrence (5%) compared to those with a HR- status (9%) in the first 5 years.

A lower tumor stage (how advanced the disease is) also reduced the patients rates of cancer recurrence by roughly 50%.

The authors concluded that HR+ expression in breast cancer is an important prognostic factor in patients with HER2+ breast cancer not on anti-HER2+ therapy. 

This study does not include the overall survival rates of the patients evaluated.