Plasma carcinoembryonic antigen (CEA) as an indicator for radical or palliative radiotherapy in patients with rectal cancer.

A study of 59 patients referred for radiotherapy because of inoperable or recurrent rectal cancers is presented in which a correlation is made between the response to radiotherapy and the pretreatment serum CEA level. Patients were treated radically or palliatively on the basis of clinical presentation and routine laboratory tests, but without regard to the plasma CEA level prior to treatment. The pretreatment CEA level was assessed retrospectively as an indicator of the response to treatment. Patients with a plasma CEA level in excess of 75 ng/ml had a poor prognosis, even after radical radiotherapy, whereas patients with plasma CEA less than 75 ng/ml responded better to treatment. These results suggest that plasma CEA is of value, indicating the need for radical or palliative radiotherapy. In patients with high plasma CEA at referral, radical radiotherapy appears to confer little benefit. Those with a low plasma CEA appear to respond better to radical radiotherapy, and this should be the preferred treatment in this group unless the clinical presentation indicates otherwise.