Basaloid squamous carcinoma: a clinical comparison of two histologic types with poorly differentiated squamous cell carcinoma.

Basaloid squamous carcinoma (BSC) of the head and neck has been shown to have a poor prognosis when compared with conventional squamous cell carcinoma (SCC). Pathologically, specimens determined to be BSC can have nearly pure basaloid features (group 1) or a mixture of basaloid and squamous features (group 2). The clinical behavior in these 2 subgroups has not been compared previously. BSC is also commonly confused histologically with poorly differentiated SCC (PDSCC). A retrospective comparison of disease stage at presentation, rate of distant metastasis, rate of local recurrence in those offered surgical resection, and rate of survival is made to compare outcomes of the 2 BSC groups and the PDSCC group. The presence of particular histologic features may be associated with poorer outcomes. Patients with BSC have advanced disease at presentation. Survival in the BSC group was less than half that in the PDSCC groups. Statistical analysis shows the 2 groups to be well matched with regard to stage and site of disease. Presence of neck nodal disease on presentation predicts poor survival. In this study distant metastases occurred in 52% of patients with BSC and in 13% of patients in the PDSCC group. The local recurrence rate is comparable for BSC and conventional SCC, with even early tumors in the BSC group recurring distantly rather than locally or regionally. Considering the high distant metastatic rate of BSC and poorer overall survival rate, a more extensive metastatic survey is indicated in these patients before surgery is recommended. We recommend that patients with a diagnosis of BSC not be included with conventional SCC groups in prospective randomized cancer protocols.