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Prophylactic Breast Irradiation (April
2003)
It is well known that nearly 80% of men
with prostate cancer treated with 1 - 3 mg of Diethylstilbesterol (DES)
will develop enlargement and tenderness of their breasts. And it is
conventional to offer radiation therapy prophylaxis, usually delivered in
three fraction prior to DES therapy. In UROLOGY 61, Jan, 2003, Widmark
reports the results of 12 months follow-up of a large Scandinavian trial
evaluating the efficacy of breast irradiation delivered before starting
Flutamide (250 mg X 3 qd) to prevent gynecomastia and breast tenderness.
At the start of Flutamide a single 3-month depot Lupron was given. Serum
testosterone measurements were made and 85% of men regained pretreatment
levels by 6 months, after which the levels either remained in the normal
range or were elevated (as is to be expected in anti-androgen therapy).
Proliferation of the glandular portion of the breast is understood to
result from increased enzymatic conversion of testosterone to estrogen,
and irradiation (RT) blunts or eliminates this response. Most of the units
(14 of 16) in the study utilized electron beam therapy (6-9 MeV) delivered
in a single 15 Gy dose.
The irradiation was significantly beneficial. 253 men were fully evaluable
at 12 months. At the onset of the study the participants were offered a
choice of having RT or none, and 174 (69%) opted for treatment. The
result: gynecomastia developed in 28% of the RT group versus 71% in the
no-RT group; breast tenderness occurred in 43% versus 75%, respectively.
As expected, the onset of breast symptoms was delayed until 1- 2 months
after the recovery of testosterone levels. (In parallel historical data,
55% of men taking DES developed gynecomastia unless RT was administered.)
Similar unwelcome breast complications develop in men taking Casodex (50
or 150 mg qd), or the Proscar/Antiandrogen combination. The March PCa
Commentary reported gynecomastia in 49% and breast tenderness in 40% of
men taking 150 mg daily of Casodex. Since it is not possible to predict
before antiandrogen therapy which men will be adversely affected or to
what extent, it seems prudent to consider offering prior RT, especially if
the RT can conveniently be delivered in one fraction.
Bottom Line: Breast RT prior to antiandrogen therapy improves
quality-of-life.
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