# Brief Report: Relationship Between Tumor Volume and Clinical Outcomes in Relapsed SCLC

## TL;DR

This study finds that tumor volume at relapse predicts survival in patients with relapsed small cell lung cancer.

## Contribution

The study is the first to show that tumor burden predicts outcomes in relapsed SCLC, using a nonlinear model.

## Key findings

- Tumor volume at relapse is a significant predictor of overall survival in relapsed SCLC patients.
- The relationship between tumor volume and survival is nonlinear, even after adjusting for other clinical factors.
- Second-line therapy and performance status also significantly affect overall survival.

## Abstract

For patients with limited-stage SCLC (LS-SCLC), tumor burden is a predictor of clinical outcomes, but there are no known data exploring whether tumor burden is a predictor of clinical outcomes in relapsed SCLC.

In this retrospective correlative study analyzing a cohort of 93 patients with relapsed SCLC, total body tumor volume at time of relapse (TV), progression-free survival (PFS), and overall survival (OS) were calculated and a Cox proportional hazards model was used to evaluate the relationship between TV and PFS and OS.

A total of 93 patients with relapsed SCLC were analyzed, of whom 70% initially had extensive-stage SCLC (ES-SCLC) and 30% initially had LS-SCLC. Eastern Cooperative Oncology Group performance status and receipt of second-line therapy were significantly associated with OS in a linear fashion (p = 0.002 and p = 0.0457, respectively). TV was significantly associated with OS in a nonlinear fashion, even when controlling for Eastern Cooperative Oncology Group performance status, response to initial therapy, chemotherapy-free interval, and receipt of second-line therapy (p = 0.0031).

TV was observed to be a predictor of OS in patients with relapsed SCLC. Further studies are needed to evaluate whether initiation of standard systemic therapy at lower TV is able to consistently improve PFS and OS in relapsed SCLC.