local management

Local Management of Invasive Breast Cancer

This section describes the multidisciplinary approach to the local
management of breast cancer by addressing the use of mastectomy,
conservative surgery (CS), and RT in a coordinated fashion, as well as
by considering the integration of local and systemic treatment.
Modified radical mastectomy is still the most common surgical
treatment for patients with invasive breast cancer in the United
States.[ref: 230,231] The term modified radical mastectomy is used to
describe a variety of surgical procedures, but all involve complete
removal of the breast, the underlying pectoral fascia, and some of the
axillary nodes. Whereas the modified radical mastectomy may not seem to
differ significantly from the radical mastectomy, it represents a major
departure from Halstedian principles of en bloc cancer surgery. The
switch to modified radical mastectomy occurred when it became
recognized that treatment failure after breast cancer surgery usually
is caused by the systemic dissemination of cancer cells before surgery,
rather than an inadequate operative procedure. In addition, by the
1970s, fewer patients with large tumors with fixation to the pectoral
muscle were being seen, making modified radical mastectomy feasible for
most women. Two prospective randomized trials demonstrated no
difference in survival between patients treated with modified radical
and radical mastectomy. These findings were confirmed in two
prospective randomized trials.[ref: 232,233] Perhaps the most
influential of the studies refuting the Halstedian concept was the
NSABP B-04 trial.[ref: 234] In this trial, clinically node-negative
patients were randomized to radical mastectomy, simple mastectomy and
nodal irradiation, or simple mastectomy with axillary observation and
delayed dissection if positive nodes developed. The failure of this
trial to demonstrate a difference in survival between groups was the
final proof that the Halstedian concept of breast cancer did not apply
to the majority of patients and was a landmark in our understanding of
the local therapy of breast cancer. Today, there are few, if any,
indications for radical mastectomy.
The strategy behind BCT is to remove the bulk of the tumor surgically
and to use moderate doses of radiation to eradicate any residual
cancer. The application of this strategy requires an understanding of
the extent and distribution of cancer in a breast with an apparently
localized tumor. This issue has been clarified as a result of the work
of Holland and coauthors. [ref: 235,236] In their initial study, [ref:
235] mastectomy specimens with unicentric tumors 4 cm or less in size
were evaluated using 5-mm sections, radiography of these thin slices,
and an average of 20 blocks per specimen for histologic evaluation.
Only 39% of specimens showed no evidence of cancer beyond the reference
tumor. In 20%, there was additional cancer, but this was confined to
within 2 cm of the reference tumor. Forty-one percent of cases had
residual cancer more than 2 cm from the reference tumor; of these, two-
thirds had pure intraductal carcinoma and one-third had mixed
intraductal and invasive carcinoma (Fig. 37.2_1). Local recurrence in
the breast occurs at or near the site of the primary tumor in most
cases,[ref: 237-240] emphasizing that this multifocal involvement is
biologically important. In a subsequent study, the amount of residual
intraductal carcinoma was evaluated.[ref: 236] Approximately 10% of
patients had prominent intraductal carcinoma (defined as a total of six
or more low-power fields of intraductal carcinoma) extending more than
2 cm from the reference tumor. These studies indicate that the extent
and amount of microscopic cancer in the vicinity of a primary tumor,
known as multifocality, is variable. These results imply that the
extent of surgical resection required in BCT varies from patient to
patient.
The published results of modern, prospective randomized clinical
trials comparing CS and RT and mastectomy have all shown equivalent
survival between the two treatment approaches, [ref: 241-247] and an
overview of all the trials (including an unpublished one) has
demonstrated comparable survival [ref: 248] (Fig. 37.2_2). These data
demonstrate that survival for most breast cancer patients is not
dependent on choice of local therapy. In addition to the results of
these trials, numerous reports from centers in Europe and North America
on the use of CS and RT have demonstrated high rates of local tumor
control with satisfactory cosmetic results. [ref: 249-253]
Despite the consistency of the evidence, the use of BCT in the United
States has shown relatively slow acceptance and considerable geographic
variation.[ref: 230,231] Studies indicate that fewer than 50% of women
with stage I and II breast carcinoma are treated with BCT. [ref:
230,231] The available data indicate that a minority of patients have
contraindications to BCT,[ref: 254,255] and that these are readily
identified with standard clinical tools, such as physical examination
and mammography including magnification views.[ref: 256] National
studies indicate that physicians continue to use inappropriate
selection criteria for BCT.[ref: 230]
The rates of recurrence in the breast at 7 to 18 years ranged from 7%
to 19% in the randomized studies using widely varying surgical and RT
techniques. [ref: 241-247] In the corresponding patients treated with
mastectomy, 4% to 14% of patients developed local recurrence,
emphasizing that mastectomy does not guarantee freedom from local
recurrence, even in women with clinical stage I and II breast
carcinoma. The nonrandomized studies with the longest follow-up
describe a persistent risk of recurrence in the breast through 20 years
of follow-up. [ref: 251-253,257] These results have been contrasted to
those seen after mastectomy, in which most local failures occur in the
first 3 years following surgery. The annual incidence rate for a
recurrence at or near the primary site is constant for years 2 through
7 after treatment, and then decreases to a low level by 10 years after
treatment. [ref: 253] In contrast, the annual incidence rate for
recurrence elsewhere in the breast increases slowly to a rate of
approximately 0.7% per year at 8 years and remains stable. [ref: 253]
Recurrences in the skin of the treated breast are a rare event
associated with a poor prognosis.[ref: 258] Whole breast irradiation is