Advances in radiotherapy for lung cancer

Abstract

In treating lung cancer, radiotherapy is the basic modality, with an established therapeutic benefit in radical and palliative settings in up to 76% of all patients. In the Czech Republic, the proportion of patients with bronchogenic carcinoma treated with radiotherapy does not exceed 25% in the long run. In the case of clinically inoperable stage I non-small cell lung cancer (NSCLC), the method of choice is stereotactic radiotherapy that provides local control in as much as 90% after three years, and its efficacy is similar to that of surgery, while having better tolerance. Postoperative radiotherapy is suitable in the case of mediastinal lymph node involvement. In locally advanced inoperable NSCLC, the standard treatment is concomitant chemoradiotherapy administered simultaneously with platinum derivative-based combination chemotherapy; blanket dose escalation above 60 Gy/6 weeks has not proved its worth because of increased toxicity with a higher mortality risk. Improved treatment results have been made possible by technical advances, such as intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), or monitoring of respiratory motion (4DCT). No clear benefit has been shown for proton beam therapy so far. In limited-stage small cell carcinoma of the lung, concomitant chemoradiotherapy is most effective, with irradiation started no later than after cycle 3 of chemotherapy at a dose of 66 Gy/33 fractions or hyperfractionation to a dose of 45 Gy twice daily for 3 weeks. Radiotherapy is also recommended in extensive-stage disease as consolidation therapy after chemotherapy with very good therapeutic response. In treating small cell lung carcinoma, prophylactic cranial irradiation is standardly recommended although careful and frequent monitoring with magnetic resonance imaging and timely treatment in the asymptomatic stage have been reported as an alternative in recent studies. In NSCLC, prophylactic irradiation reduces the proportion of patients who develop brain metastases from 30% to 8%, but it has not been shown to prolong survival.