Involved-Field Radiation Therapy (IF-RT) for Non-Small Cell Lung Cancer (NSCLC)

The pattern and incidence of lymphatic spread of non-small cell lung cancer (NSCLC) is differentiated according to location, size and histologic type of primary tumors. As the primary tumor size increases, the incidence of lymphatic metastasis increases. Ogata et al reported the incidence of mediastinal lymphatic metastasis increased from 24% for tumors under 2 cm in size to more than 40% for tumors larger than 5 cm 1). Hata et al analyzed 192 lymphoscintigraphies in 179 patients to determine the lymphatic drainage from each segmental bronchus into the mediastinum 2). For the right lobes, most of the lymph flowed into the right supraclavicular nodes through the subcarina or right paratracheal nodes. There were few drainages to the left supraclavicular nodes through subcarinal nodes. In contrast, the lymphatic drainage from the left lung was more variable, and four routes were determined, as follows.