Combined Modality Therapy for Limited Small Cell Lung Cancer

Abstract

Combined modality therapy for limited small cell lung cancer (SCLC) is indicated for local control. Chemotherapy by itself produces excellent responses but an unacceptably high rate of local failure. Small cell lung cancer is exquisitely responsive to a variety of chemotherapeutics and to radiation therapy. The problem with unimodal therapy, i.e., radiotherapy or chemotherapy, is that each modality by itself is inadequate. Waiting too long to use radiotherapy may allow resistant subclones to develop. Once resistant cells leave the local site and colonise distant sites, the patient is doomed. Radiotherapy cannot control occult distant SCLC. However, used too intensively or too early, it may prohibit the use of full doses of chemotherapy needed to control the clinically occult distant disease. Although debate continues, there is an established role for thoracic radiotherapy in limited disease, but use of radiotherapy for chest or other sites of disease in extensive small cell lung cancer is not established. There are 3 general methods of integrating chemotherapy with radiation treatment: 1) sequential therapy, 2) alternating therapy and 3) concurrent therapy. The beneficial and the toxic effects of combined modality therapy may be strongly dependent on the timing. The intrinsic toxicities of the chemotherapy as well as the volume, total and daily dose of thoracic radiotherapy may also influence both toxicity and disease control.