ASTRO: Proton beam therapy effective for treating non-small cell lung cancer

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Proton beam therapy (PBT) may provide safe, effective and superior treatment for inoperable Stage I non-small cell lung cancer (NSCLC) compared with other nonsurgical modalities, according to a study published in the October edition of International Journal of Radiation Oncology, Biology and Physics.

"Recent interest in stereotactic radiotherapy and particle beam therapy for the treatment of lung cancer stems from the ability of these modalities to achieve improved conformality of the treatment field," Hidetsugu Nakayama, MD, PhD, of the University of Tsukaba in Japan, and co-authors wrote. Conventional radiotherapy is frequently used to treat non-small cell lung cancer, yielding five-year survival rates between 6 and 31 percent. NSCLC is the leading cause of cancer-related deaths worldwide.

The authors noted that PBT offers an advantage in treating Stage I NSCLC because of the method's superior dose localization. In the study, the authors retrospectively evaluated the effects of PBT on 55 patients (a total of 58 tumors) with Stage IA or Stage IB medically inoperable NSCLC. Forty-one of the tumors were located peripherally and 17 centrally. The median participant age was 76.7 years.

Overall patient survival after two years was 97.8 percent; two patients died non-cancer related deaths. Progression-free survival and local control of tumors for all patients after two years were 88.7 and 97 percent, respectively. Only two patients experienced deterioration of lung function, while two additional patients had Grade 3 pneumonitis.

The authors noted that their progression-free survival rate and local control rate were comparable to other studies "despite the relatively low total [radiation] dose delivered." There was no statistically significant difference between progression-free survival rates of T1 and T2 tumors.

Of the 58 tumors treated, seven recurred, including three Stage IA and four Stage IB. One local progression was recorded, and three mediastinal recurrences and three recurrences outside the irradiated volume in the lung were found.

"Survival and progression-free survival after PBT were comparable to those for surgical resection, and no adverse effect on pulmonary function was seen after therapy. Therefore, PBT seems to be safe and effective—if not superior to other nonsurgical modalities—for patients with Stage I NSCLC who are poor surgical candidates," the authors concluded.