The risks of cancer returning; do hormones play a role?

The authors aimed to determine the risks of cancer recurrence (the cancer returns) between the time of hormone or endocrine therapy and the 10 years following. 

Endocrine therapy is used as treatment against particular cancers that may grow in response to hormones natural to our body. This includes hormone estrogen and progesterone, among others.

Tamoxifen (Nolvadex) is one drug used for this purpose. 5 years has been the standard length of endocrine therapy using this drug. Some studies suggest that an extended course of treatment may benefit patient prognosis (outlook) and reduce the risk of recurrence.

Prognostic tools, however, have yet to be developed to identify which patients this extended treatment may benefit. 

The aim of this study was to determine the possible prognostic factors that result in an increased risk of developing recurrent cancer. This study looked at post-menopausal women with estrogen receptor positive (ER+; proteins present on cancer cell surface) in particular.

A total of 1,125 women were evaluated for risks of cancer recurrence in both 0-5 years and 5-10 years following endocrine treatment. 

Out of these women, 215 women experienced a local recurrence (cancer returns at or near the original tumor site) and 164 women experienced a distant recurrence (cancer that has spread to areas farther away from the original tumor site) within these 10 years.  Women whose tumors expressed high levels of ER had a 12% lower risk of recurrence in years 0-5 compared to those with lower levels of ER. High levels of ER were associated with a 19% increased risk of recurrence in years 5-10 compared to lower levels of ER.

Furthermore, it was seen that those with human epidermal growth factor 2 positive (HER2+, dependent on HER2 for growth) breast cancer had an increased chance of developing recurrent cancer in years 0-5 compared to those with HER2- breast cancer. The risk of recurrence was equal 5-10 years following treatment.

The authors concluded that patients with estrogen-sensitive tumors were the group most likely to benefit from an extended period of endocrine therapy. 

This study did not actually involve patients with HER2+ breast cancer; their information was sourced from literature. Women with HER2- breast cancer were involved.