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After 10 years, postmastectomy radiation is shown to improve local
control but not overall survival in women with breast cancer and one to
three positive nodes
After 10 years of follow-up, postmastectomy radiotherapy improved local control but not overall survival in women with breast cancer and one to three
positive lymph nodes, even after controlling for poorer prognostic features.
M
oses M. Tam, MD, of New
York University Langone
Medical Center, New York,
explained that the role of postmas-
tectomy radiation in women with
breast cancer and one to three
positive lymph nodes in the set-
ting of modern systemic therapy is
controversial.
“I wanted clarification,” Dr Tam
said, “on the controversy regarding
the need for postmastectomy radia-
tion therapy in patients with one to
three positive nodes. In fact, just
last week, the ASTRO/American
Society of Clinical Oncology/Soci-
ety of Surgical Oncology released a
consensus statement on this subject.
They stated that postmastectomy
radiation therapy confers a clear
disease control and survival benefit
in patients with T1–T2 disease and
one to three positive nodes.”
He continued, “Subsets of pa-
tients may be at such low risk of
disease recurrence that potential
toxicities may outweigh the ben-
efit of postmastectomy radiation
therapy. Our analysis evaluated one
of those patient subsets, essentially,
those who received modern systemic
therapy.”
Dr Tam and colleagues set out to
investigate the effect of postmastec-
tomy radiotherapy on breast cancer
outcomes at 10-year follow-up in
women enrolled on Breast Cancer
International Research Group 005,
a phase 3 trial of doxorubicin/cy-
clophosphamide with concomitant
versus sequential docetaxel.
Individual patient data at 10-year
follow-up were analysed for 1649
women treated on the control arm
(sequential docetaxel). All women
were node positive, HER-2 nonam-
plified. They underwent mastectomy
or lumpectomy with negative mar-
gins followed by axillary lymph node
dissection with at least six lymph
nodes removed.
Postmastectomy radiotherapy was
given at the investigator’s discretion.
Adjuvant hormonal therapy was
given in hormone-positive disease.
Primary analysed outcomes in-
cluded local control, locoregional
control, distant metastasis, and
overall survival.
Statistical analysis of categorical
data was performed with X2 test.
Survival curves were plotted using
the Kaplan-Meier method, and sur-
vival estimates were obtained using
log-rank test and Cox’s proportional
hazard model using SPSS statistical
software. A propensity score analy-
sis was performed with R statistical
package.
Five hundred twenty-three
women underwent mastectomy
with one to three positive lymph
nodes. Thirty-nine percent received
postmastectomy radiotherapy, which
included the chest wall, supracla-
vicular field (71%), and internal
mammary nodes (27%). Women
receiving postmastectomy radio-
therapy were significantly younger,
had more positive nodes, and had
more advanced T stage than patients
who did not receive the treatment.
Postmastectomy radiotherapy im-
proved 10-year local control (99%
vs 94%, P = 0.006) significantly
versus patients who did not receive
postmastectomy radiotherapy. The
therapy did not improve 10-year
distant metastases (20% vs 17%) or
overall survival (86% vs 84%) versus
patients who did not receive post-
mastectomy according to the use of
propensity score analysis. A trend
toward locoregional control was
observed (95% vs 92%, P = 0.08).
Subgroup analysis including larger
tumours, poorly differentiated dis-
ease, two or three positive lymph
nodes, or premenopausal status
did not identify a patient cohort in
which postmastectomy radiother-
apy predicted for improved overall
survival.
Dr Tam concluded after 10 years
of follow-up, postmastectomy radio-
therapy improved local control but
not overall survival in women with
one to three positive lymph nodes,
even after controlling for poorer
prognostic features.
“We found,” he commented, “that
patients treated with modern sys-
temic therapy experienced excellent
outcomes in local control and over-
all survival, regardless of whether
they received radiation therapy. We
also found, however, that radiation
therapy provides a clear local control
benefit and a trend toward improved
locoregional control once we ad-
justed for imbalances in underlying
patient characteristics.”
He continued, “On multivariate
analysis, we identified younger age
(<40 years) and higher-grade disease
were associated with higher risk of
locoregional recurrence and death.
These patients, therefore, may be
more likely to benefit from radiation
therapy.”
“Future directions will involve
a larger cohort of patients to help
answer the question of whether ra-
diation therapy impacts overall sur-
vival in the era of modern systemic
therapy.”
Future directions will involve a larger cohort of patients to help
answer the question of whether radiation therapy impacts
overall survival in the era of modern systemic therapy.
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