The Next Frontier: Radiation. How much? How long?

For the most part, all patients who opt for lumpectomy undergo at least whole breast radiation in addition to surgery for local disease management (not all mastectomy patients end up having radiation).

The big question, in my case, was what radiation regimen I would pick. Basically, in terms of tissues to irradiate, I was given two options at one institution (whole breast only, or whole breast plus axillary, infraclavicular, and supraclavicular nodes) and one option at another (in radiation oncology lingo, "high tan"- meaning that they would get whole breast plus some, but not all, of the lymph nodes). In both cases, a post-treatment radiation "boost" to the lumpectomy site was recommended for improved local control.

How much?

Patients enrolled in the Z-11 trial (which looked at radiation versus axillary dissection in patients with 1-2 positive nodes, including clinically-negative nodes with micromets) underwent whole breast radiation, and whole breast radiation was found to be non-inferior to axillary dissection in terms of long-term breast cancer recurrence.

But-- the study did not address the question of whether nodal radiation improved outcomes when compared to whole breast radiation. Very recently, early results of the MA-20 trial demonstrated improved disease-free survival in patients who received expanded nodal radiation; the major downsides were a slightly higher risk of lymphedema and a significant risk of hypothyroidism. Results of the MA-20 trial were consistent with other recent studies evaluating expanded radiation.

How long?

In addition to the question of breast versus nodal radiation, there was also a question of how to break the radiation up over time.

Overall, I had three options:  hypo fractionated (i.e., short-course, 4 weeks)  standard (i.e., long-course, 6 weeks) or two weeks of radiation as part of a phase III clinical trial.

Since the results of the NEJM trial, hypofractionated therapy has become more and more standard. However, in interpreting clinical trial results, it is important to keep in mind the patient population involved. In the case of the short-course radiation, overall the patients were low-risk (only 25% under 50, 19% with high-grade disease, 11% with adjuvant chemotherapy) so my clinicians were concerned that the trial was not "generalizeable" to a patient like me. Another important note is that hypofractionated therapy was only offered for whole breast radiation-- not for expanded nodal radiation.

Drum roll please…

Overall, given the grade of my tumor (3) and the presence of certain pathologic features, prior work suggested that the radiation part of my therapy is very very important for me. So, I opted for the most conservative course: six weeks, including a lumpectomy boost, with radiation to local nodes. The major downside to adding in the nodal radiation is a risk of hypothyroidism (on the order of one in five patients), and clinical medicine is vey good at managing hypothyroidism. So, unlike with the ACTH versus the TCH, I felt that the benefits of the more aggressive radiation outweighed the harms, and went for it.