Proton therapy with concurrent chemotherapy for non-small-cell lung cancer: technique and early results

Proton therapy can deliver a more conformal dose distribution than photon radiation and may allow safe dose escalation in stage III lung cancer. Early outcomes are presented here for patients who received proton therapy with concurrent chemotherapy for non-small-cell lung cancer (NSCLC).

Nineteen patients with regionally advanced NSCLC were treated with concurrent chemotherapy (carboplatin and paclitaxel [n = 18]) and proton therapy from August 2008 to April 2010 either with (n = 7) or without (n = 12) induction chemotherapy. Eighteen patients had stage III NSCLC, and 1 patient had stage IIB disease. The median proton therapy dose was 74 cobalt gray equivalent (CGE) in 2 CGE fractions with 18 patients who received ≥70 CGE. Twelve patients also received selective nodal proton therapy to the adjacent uninvolved nodal regions, with a median dose of 40 CGE (range, 40-46 CGE). The patients were routinely evaluated for treatment-related toxicity and disease progression every 3 months, with a history, physical, and computed tomography or positron emission tomography-computed tomography.

The median follow-ups for living patients were 15 and 16 months (range, 7-26 months), respectively. Nonhematologic and hematologic acute grade 3+ toxicity (<90 days) developed in 1 and 4 patients, respectively. Two of 16 patients assessable for late toxicity (≥90 days) developed a significant grade 3+ nonhematologic late toxicity, whereas 1 patient developed a grade 3+ hematologic late toxicity. Local progression was the site of first relapse in one patient.

Mediastinal proton therapy with concomitant chemotherapy was associated with acceptable toxicity. Although encouraging, longer follow-up with more patients is needed to confirm the long-term efficacy of this treatment.