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left axillary lymphadenopathy, suggestive of axillary nodal metastatic disease. She was also found to be negative for systemic
metastatic disease, excluding the existence of a lung primary.
Medical oncology recommended neoadjuvant carboplatin and etoposide, a standard double-agent regimen used in
neuroendocrine tumors, including SCLC. Neuroendocrine
tumors are highly replicative, as seen in this patient's proliferative index of 100%. Etoposide inhibits topoisomerase, which
prevents DNA replication, therefore halting tumor growth (3).
Carboplatin induces cross-linking of DNA strands to further
prevent DNA replication and leads to cell death (4). The decision to undergo neoadjuvant, rather than adjuvant, therapy in
our patient was twofold. Neoadjuvant therapy can be clinically
monitored for eﬀectiveness by examining the size of the mass
during treatment. If the tumor demonstrates progression during neoadjuvant therapy, the clinician can change regimens or
proceed directly to surgery. Additionally, after resection, the
tumor can be evaluated microscopically for the exact degree of
response to treatment.
After completing her course of chemotherapy, the patient
had almost complete resolution of her palpable breast and axillary masses. She then underwent left skin and nipple-sparing
modiﬁed radical mastectomy, which included a left axillary
lymph node dissection. No sentinel lymph node biopsy was
performed, as the patient's axillary nodes were already known
to be involved. Per the patient's wishes, this surgery was immediately followed by breast reconstruction with a tissue expander.
Since the landmark NSABP B-06 study, published in 1985,
treatment of breast cancer with lumpectomy and adjuvant
radiation has been known to be oncologically safe, providing
the same long-term survival as a mastectomy (5). Therefore,
aside for a few contraindications, patients are given the option
to undergo either mastectomy or lumpectomy with adjuvant
radiation. Reasons for deciding between the two are multiple
and diverse. This patient elected to undergo mastectomy.
Final pathology demonstrated a 0.1 mm microscopic focus
suspicious for residual tumor, and an additional 1.2 cm area
of high-grade ductal carcinoma in situ, negative for estrogen
receptor, progesterone receptor, and human epidermal growth
factor receptor. The 7 axillary lymph nodes examined histologically were found to be negative for active invasive disease. Given
that the patient had clinically palpable axillary lymph nodes,
which were active on PET scan, we believe that her neoadjuvant
therapy completely cured her nodal disease. On follow-up CT
scans of the chest, abdomen, and pelvis, the patient had no
evidence of residual disease. She is now undergoing postoperative care with routine screening right breast mammogram and
bilateral breast exam.
DISCUSSION
The early diagnosis of rare breast cancers will continue to
increase along with that of typical breast cancers as screening and
diagnostic modalities continue to improve. Given the paucity
of atypical diagnoses, the treating physician is left with limited
consensus data to guide his or her management. Treatment of
our patient's primary breast small cell carcinoma involved mulApril 2017

tidisciplinary application of principles learned in the treatment
of SCLC as well as other extrapulmonary small cell carcinomas.
Pulmonary SCLC constitutes 95% of all small cell cancers
(1). Standard management of pulmonary SCLC is complex;
however, it essentially entails 4 cycles of cisplatin and etoposide
along with thoracic radiotherapy with or without lobectomy.
Prophylactic cranial irradiation is also given to patients who
have proven response to chemotherapy and radiation (6). The
delivery of this multimodal treatment has a proven survival
beneﬁt for patients with SCLC. Standard staging for SCLC
consists of tumor, node, and metastasis evaluation. For practical treatment, however, a unique staging system, the Veterans
Administration Lung Study Group, was developed. Under this
system, SCLC patients are categorized as either limited disease
or extensive disease (7). Under contemporary multimodal treatment, SCLC patients with limited disease have a 13.3% 5-year
survival rate. SCLC patients with extensive disease have a 1.2%
5-year survival rate (8). Although this is a bleak outcome, survival without treatment rarely exceeds more than a few months.
For the remaining 4% to 6% of small cell cancers that are
extrapulmonary, treatment algorithms and prognostic risk factors are less deﬁned (1). The question at hand is whether or not
the treatment of SCLC can be applied to extrapulmonary small
cell cancer with similar results. A study published in 2010 from
Peter MacCallum Cancer Centre in East Melbourne, Australia,
attempted to answer this question. This retrospective review determined the recurrence rate, 5-year survival rate, and prognostic
risk factors of 120 cases of extrapulmonary small cell cancer
treated with the same algorithm as SCLC. Patients were staged
according to the aforementioned Veterans Administration Lung
Study Group staging system. The treatment, in general, consisted of 4 cycles of cisplatin/carboplatin and etoposide, radiation therapy to the primary site and involved lymph nodes to
a dose equivalent of at least 50 G in 2 G fractions, and surgical
resection if feasible. Prophylactic cranial irradiation was administered to 7 of the 120 patients. Recurrence-free survival at 1 year
ranged from 13% (genitourinary) to 64% (head and neck). The
overall 5-year survival rate was 25.4% for patients with limited
disease and 0% for patients with extensive disease. Improved
overall survival was seen in patients with associated weight loss,
the use of deﬁnitive radiation therapy, higher-dose radiation
therapy, higher number of chemotherapy cycles, and the combination of chemotherapy and radiation (8). Interestingly, surgical
resection was not associated with an improved outcome. The
use of prophylactic cranial irradiation was determined to be a
positive prognostic factor for survival; however, given the low
incidence of brain metastasis in the nonprophylactic cranial
irradiation group, the study concluded that prophylactic cranial
irradiation should not be a part of extrapulmonary small cell
cancer treatment.
Prior case reports of primary small cell carcinoma of the
breast suggest that a breast primary may carry a higher survival
rate than other primary sites. A report of 9 cases from 1996 to
1999 at New York Presbyterian Hospital found all 9 patients
alive at follow-up 3 to 35 months after treatment. All 9 patients
presented with disease limited to either the breast or the axilla.

Primary small-cell carcinoma of the breast

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Table of Contents for the Digital Edition of Baylor University Medical Center Proceedings April 2017