SAN ANTONIOFollow-up studies from five clinical
trials at M.D. Anderson suggest that postoperative supplemental radiotherapy to
the axillae in patients with stage II-III breast cancer is often unnecessary,
since failure in the dissected axillae is uncommon. The report was presented at
the 23rd annual San Antonio Breast Cancer Symposium.
Postmastectomy irradiation to the axillae has been shown in
three trials not only to improve local-regional control but also to potentially
improve survival in patients at high risk for failure.
The indications for this approach at M.D. Anderson are the
involvement of four or more axillary lymph nodes, tumor size greater than
5 cm, or 2 mm or more of extranodal extension.
While the chest wall is always irradiated in these patients,
indications for radiation to the regional nodes in addition to the chest wall
are somewhat controversial, explained Angela Katz, MD, a radiation oncologist
at M.D. Anderson and the study’s lead investigator.
The aim of this retrospective review of 1,031 patients was to
determine if there is a subgroup of patients for whom postoperative regional
nodal irradiation after surgery is particularly beneficial and to identify
patients for whom specialized radiation fields should be added, she said.
The study was based on the regional nodal failure patterns of
patients with stage II-III breast cancer treated in M.D. Anderson clinical
trials from 1975 to 1994 and followed for almost 10 years.
The women had tumors of 2.5 cm; median age was 49 years. They
received definitive surgery (mastectomy, including a level I-II axillary
dissection) and doxorubicin-based systemic therapy but no radiotherapy.
Patient records were reviewed and all regional recurrences,
including isolated failures as well as failures with or without distant
metastases, were recorded.
There were 141 node-negative patients, 466 patients with one to
three positive nodes, and 319 patients with four or more involved nodes.
Ten-year overall survival for the group was 65%; disease-free
survival was 55%; 19% of patients had a local-regional recurrence. There were
179 local-regional occurrences, of which 124 were isolated events without
distant metastases. Sixty-four percent of patients were free of distant
metastases at 10 years, Dr. Katz
Local-Regional Recurrence Patterns
The 179 local-regional failures were in the following sites:
68% chest wall, 40% supraclavicular nodes, 14% axillae, 7% intraclavicular
nodes, and 8% internal mammary nodes. More than one site could be involved.
Failure in the dissected axillae, however, was rare, occurring
in only 25 patients, for a 10-year actuarial rate of 3% in this group. Of
these, 17 were isolated regional failures.
"None of the factors we looked at predicted for a higher
rate of failure in the dissected axillae, including the number of involved
nodes, an increasing percentage of involved nodes, larger nodal size, the
presence of extranodal or extracapsular extension, or the extent of the
axillary dissection," she said.
Failure in the undissected axillae or the supraclavicular area
was more common, occurring in 75 patients for an 8% rate at 10 years.
Significant predictors of failure in this group of patients
included the involvement of at least four axillary lymph nodes, involvement of
20% of the nodes examined, and the presence of 2 mm or more of extranodal
extension. Ten-year actuarial failure rates for patients with these factors
were 15%, 14%, and 20%, respectively, Dr. Katz reported.
"Patients with 2 mm or more of extranodal extension are
at increased risk of local-regional recurrence. However, most of these
recurrences involve the chest wall (74%) or the undissected axillae
(50%)," Dr. Katz said.
She noted that failure in the dissected axillae does not appear
to be increased in these patients. "It is only 5% at 10 years, or 12% of
the failures in these patients. So extracapsular extension appears to be a
marker of more aggressive disease but not necessarily of disease left in the
axillae," she said.
The findings suggest that failure in the dissected axillae is
uncommon, she said. "Supplemental radiotherapy, therefore, is rarely
warranted in these patients, and extracapsular extension is not an indication
for it," she said.
Indications for irradiation to the undissected axillae in
addition to the chest wall include the presence of four or more involved nodes,
involvement of more than 20% of the nodes examined, or at least 2 mm of
extranodal extension, she reiterated.