Metachronous cancer: prognostic factors including prior irradiation.
In this article we evaluate two factors that may be responsible for the reported increased mortality rate in metachronous cancers: prior radiation therapy and stage at presentation. A select group of 358 patients was split into three groups: no prior cancer (group 1), prior cancer treated with radiation therapy (group 2), and prior cancer treated with surgery alone (group 3). We compared survival among the three groups according to stage (T1 or T2 vs. T3 or T4) using the Lifetest procedure. Survival in patients with advanced (T3 or T4) cancers was uniformly poor, and survival in patients with low-staged (T1 or T2) cancers was disproportionately poor only for patients in group 2. Metachronous cancers are not necessarily more lethal, except when the cancer arises within prior irradiated tissue. Initial treatment decisions for patients with primary cancers must always provide for the contingency of a metachronous cancer, and the judicious use of radiation therapy is essential.