Primary SqCC of the breast is believed to arise directly
from the epithelium of the mammary ducts although
another theory is that the tumor arises from foci of squamous
metaplasia within a pre-existing adenocarcinoma of
the breast. Some cases of primary SqCC were reported
to arise from the capsules surrounding the silicone breast
prostheses[
2].
Metastasis to axillary lymph nodes in primary SqCC
are uncommon with an incidence of 0 to 22%. In contrast, rates of axillary involvement as high as 40% to 60% have
been reported at presentation in infiltrating ductal carcinoma
of the breast. In our patient the tumor was 5.5 cm in
diameter and she had no metastatic involvement of axillary
lymph nodes.
No consistent mammographic findings have been described
for SqCC. Calcification in the squamous tissue is
occasionally seen on mammography. In our case multiple
heavily calcified fibroadenomata was seen in the mammography.
SqCC of the breast is mostly ER and PR negative. This
is the expected way of presentation of a tumor comprised
solely of squamous cells. Hormone receptors were negative
in our patient.
When we diagnose SqCC in the breast, it is necessary
to exclude the presence of metastasis from an extramammary
primary or a possible occult primary on detailed
clinical assessment, investigations and follow-up. The
most common sources of metastatic SqCC to the breast
are the lung, uterine cervix, esophagus, skin and oropharynx.
Further special investigations should be governed by
clinical presentation. Our patient had a history of cyst hydatid
operation from her lung and we performed FOB to
exclude the lung cancer.
As there are fewer cases of primary SqCC than adenocarcinoma
of the breast, optimal treatment and the prognosis
are both unclear. Postoperative role of adjuvant radiation
therapy remains unclear in the absence of clinical
trials. But SqCC is usually radiosensitive, although sporadic
reports are conflicting. Adjuvant chemotherapy is often
suggested rather than endocrine therapy because of ER and
PR negativity[1]. The optimum choice of chemotherapeutic
agents is unknown. One review suggests that SqCC of
the breast is not sensitive to chemotherapeutic agents commonly
used for ductal adenocarcinoma such as cyclophosphamide,
methotrexate, 5-FU and adriamycin[3]. Stevenson
et al.[4] suggested combining cisplatinum, 5-FU and
adriamycin, and Behranwala et al.[1] suggested mitomycin
and mitoxantrone in the adjuvant treatment of the disease.
Our patient was treated with 6 cycles of CAP (cyclophosphamide,
adriamycin and cisplatinum) chemotherapy and
adjuvant radiotherapy and there is no evidence of disease
for thirteen months of follow-up. Since cisplatinum is the
main drug in the treatment of squamous cell carcinoma and
cyclophosphamide and adriamycin is the standard of adjuvant
treatment of breast cancer we suggest that combining
these three chemotherapeutics can be considered to be the
ideal adjuvant treatment for SqCC of the breast.
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