What is the goal of adjuvant (post-surgical) therapy?

Let's talk about the numbers for a minute. Say about 5 percent of the people with a lumpectomy and radiation therapy ultimately end up with an in-breast local recurrence, which is 1 in 20. That means 1 in 20 ends up with a mastectomy because of a recurrence and that 19 in 20 get to avoid mastectomy. So it really comes down to a question of what matters to the individual patient.

Still, there are many patients for whom the yearly mammogram and maybe MRI and physical exam is anxiety provoking, and some of those people will elect bilateral mastectomy instead. But for most patients, preserving the breast seems to be the priority, and they're willing to put up with this small risk of local recurrence in exchange for the benefits of keeping their breast.

What is the goal of adjuvant (post-surgical) therapy?

The goal of adjuvant therapy is to kill cancer cells that might have spread beyond the breast and lymph nodes before the surgery took place. They're out and about in the body, and we don't have a way of identifying exactly where they are so we have to treat with medicines that circulate throughout the body and kill cancer cells wherever they may be.

How much does chemotherapy reduce risk of recurrence?

Chemotherapy across the board lowers the annual rate of recurrence by about 24 percent. And this adds up, depending on the absolute risk of a patient, to roughly a one-fifth to one-quarter or slightly better reduction in risk at five years. That's the average for old chemotherapy regimens like CMF (Cytoxan, methotrexate and fluorouracil). Most modern chemotherapy regimens that work better than CMF will obviously offer even greater advantage.

How is someone's personal benefit from chemotherapy assessed?Chemotherapy decision-making is really challenging for everybody involved. We first have to ask ourselves what's the benefit of chemotherapy generally. Then we have to apply that to the individual patient, which means calculating her individual risk of recurrence.

Once we get into that discussion, adjuvant chemotherapy is not generally recommended unless women will likely reduce their risk of recurrence with chemotherapy by at least 1 percent. Some people will set it even higher. Clinicians often set it at 2 or 3 percent, but patients surveyed after treatment typically set it at 1 percent.