SABCS 2014 The SOFT Trial

Each year, there are reams of fascinating research findings that are presented at the SABCS. To choose the most significant one is definitely a challenge. However – since I’ve been asked! – I would say that the most interesting results came out of the SOFT (Suppression of Ovarian Function Trial) trial.

Let me give you a little background here. As I’m sure you already know, in hormone-receptor-positive breast cancer, estrogen can stimulate the growth of breast tumor cells. We don’t want that now do we? So, one goal of treatment is to prevent estrogen from helping the breast tumor cells grow.

After a premenopausal woman has surgery (e.g., a lumpectomy or mastectomy), to reduce the risk of the cancer from recurring, the traditional treatment for women diagnosed with early-stage hormone-receptor-positive breast cancer has been hormonal therapy called Tamoxifen. Taken in a pill, this drug binds to estrogen receptor and blocks the action of estrogen, so that the breast tumor cells that need estrogen to divide stop growing and die. It also lowers the overall amount of estrogen in the body. Good stuff, right?

Well yes, BUT researchers wanted to see if they could do even better to prevent breast cancer recurrence (love that as a former breast cancer patient myself!).

This is where the SOFT trial comes in. Researchers were curious about whether adding ovarian suppression to either Tamoxifen OR Aromasin (chemical name: exemestane) to see how well they work compared to Tamoxifen alone in treating premenopausal women who have undergone surgery for hormone-responsive breast cancer.

Please allow me to explain a few things first. As an aside, I know that there is so much background information that comes in this explanation, but bear with me because it will all make sense shortly.

Ok, so ovarian suppression uses medical interventions (e.g., drugs or surgery) to stop the ovaries from making estrogen and thereby preventing a tumor from getting the estrogen that it needs to grow. Ovarian suppression puts women into a state similar to a natural menopause in that it lowers hormone levels and stops menstrual periods.

Aromasin is a type of drug called an aromatase inhibitor that is another option in our never-ending quest to eliminate estrogen in hormone-receptor-positive breast cancer. It works by BLOCKING the enzyme aromatase, which turns the hormone androgen into small amounts of estrogen in the body. What this means is that less estrogen is available to stimulate the growth of hormone-receptor-positive breast cancer cells. Now the key is that Aromasin does not stop the ovaries from making estrogen, so this drug ONLY works when the ovaries are suppressed or – in other words – when women are in menopause.

Still with me? Ok, so back to the SOFT trial. In one aspect of this study researchers looked at the benefits – what they referred to as disease-free survival – of ADDING ovarian suppression to the drug Tamoxifen in women diagnosed with early stage hormone-receptor-positive breast cancer. They also studied ADDING ovarian suppression to Aromasin to see how well they work compared to Tamoxifen alone in treating premenopausal women who have undergone surgery for hormone-responsive breast cancer.

This SOFT trial – which took five years to complete, by the way! – revealed that in premenopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer, the women who got the drug Tamoxifen AND ovarian suppression did better than taking Tamoxifen alone.

Further – and this is the biggie – the medication Aromasin combined with ovarian suppression reduced recurrence risk better than Tamoxifen and ovarian suppression. The group that benefitted the most was women under the age of 35, in other words those who are typically premenopausal.

These outcomes are potentially practice changing (which is why I picked it as the most significant of findings). The bottom line is this: in premenopausal women who have had surgery for hormone-responsive breast cancer, to reduce the risk of the cancer coming back, INSTEAD of taking Tamoxifen for 5-10 years, oncologists may begin recommending ovarian suppression (either in the form of medication or surgery) combined with Aromasin.

In fact, after my hysterectomy this fall, I have a sneaking suspicion that my Oncologist is going to want to add Aromasin to my daily regimen. Will keep you posted, of course!