Which of the following statement(s) is/are true concerning the histologic variants of invasive breast carcinoma?

b. Medullary carcinomas, although often of large size, are associated with a better overall prognosis than common invasive ductal cancers

d. Invasive lobular carcinoma is associated with a higher incidence of bilateral breast cancer

Although the breast is composed of both lobular and ductal elements, most breast cancer arises in the ductal elements. Invasive ductal carcinoma accounts for 70% to 80% of all cases of breast cancer. Although there is no single microscopic feature specific for infiltrating ductal carcinoma, it can be recognized histologically as an invasive adenocarcinoma involving ductal elements. The malignant ductal cells are often dispersed within the fibrous stroma, leading to the appellation of scirrhous carcinoma. A number of less common types of breast cancer arise from the ductal epithelium and are hence classified as variants of invasive ductal carcinoma. There are distinct histologic criteria for classifying these lesions; these criteria must be met throughout the entire tumor. Prognostically, histologically pure examples of these variant tumors are associated with a better long-term survival than ordinary type invasive ductal carcinoma. When mixed histologies are encountered, the clinical behavior parallels that of the invasive ductal element, not the other sub-type. Hence, these mixed tumors are considered together with pure invasive ductal carcinoma for prognostic purposes. In many cases, when areas of in situ ductal carcinoma are seen, the presence of an in situ component does not adversely affect prognosis, although it jeopardizes the attempts at breast conservation. Medullary carcinoma is one of the more common variants, accounting for approximately 6% of all invasive breast cancers. These tumors may grow to be a rather large size within the breast (5 to 10 cm) and are characteristically well-circumscribed. Mucinous carcinoma, also referred as colloid carcinoma, is encountered in 1% to 2% of breast cancer cases. Invasive lobular carcinoma arises from the lobular component of the breast and in most series accounts for approximately 10% of breast cancers. Almost every series has stressed the higher incidence of bilateral cancer in patients with invasive lobular carcinoma. The contralateral breast is involved either synchronously (3% of patients) or metachronously in up to 30% of patients.