A Reasonable Definition of Oligo-Recurrence in Non-Small-Cell Lung Cancer

The concept of oligo-recurrence in non-small-cell lung cancer (NSCLC) has been suggested to describe the possibility of achieving long-term survival or even cure with local therapy for recurrence despite having recurrent disease. Oligo-recurrence involves a limited number of metachronous recurrences that can be treated with local therapy. However, the number of recurrences that constitutes an oligo-recurrence has varied among studies and remains to be defined. The aim of this study was to elucidate the number of recurrences that constitutes an oligo-recurrence in NSCLC.

We retrospectively reviewed 577 patients with NSCLC who had underwent complete resection and developed recurrence between 1990 and 2009, and these patients were evaluated. Patients were categorized according to the number of recurrences, and postrecurrence survival (PRS) was compared between groups.

Altogether, 270 patients underwent local therapy for all recurrent lesions. In these patients, sex (female), histological type (adenocarcinoma), gene mutation status, recurrence-free interval <1 year, and presence of 1 or 2 recurrences were factors associated with prolonged PRS. Additionally, all patients who maintained a cancer-free status for at least 5 years after treatment for recurrence and were considered possibly cured, had 1 or 2 recurrences.

Among patients receiving radical local therapy, the PRS was particularly longer among those with 1 or 2 recurrences, and these patients were able to aim for postrecurrence cure. Thus, a reasonable threshold to define oligo-recurrence in NSCLC is 1 or 2 recurrences that can be treated with local therapy.