The majority of patients with breast cancer can be treated by partial
mastectomy and radiation therapy. Ineligibility for breast conservatio
n usually is related to previous radiation or the inability to receive
radiation for other reasons. For patients who can receive radiation,
selection for breast conservation involves the estimation of the risk
for in-breast recurrence and the ability to achieve a satisfactory cos
metic result. Multiple sites of cancer within the breast and the inabi
lity to attain negative pathologic margins on the excised breast speci
men are predictive for an increased risk of recurrence. The cosmetic r
esult is compromised by excision of large volumes of breast tissue. Al
though the size of the tumor is not an important consideration for in-
breast recurrence, the relation of the size of the tumor, and hence th
e volume of tissue excised, to the size of the breast is an important
cosmetic consideration. Compared to invasive ductal carcinoma, an exte
nsive intraductal component or invasive lobular carcinoma tends to be
more difficult to define within the breast and may require excision of
a large volume of tissue to obtain negative pathologic margins.