Spontaneous regression of non-small cell lung cancer that progressed after multiple chemotherapies: A case report.

Spontaneous regression (SR) of cancer is defined as a complete or partial, temporary or permanent disappearance of all or at least some relevant parameters of malignant disease with inadequate or no treatment. SR of cancer is an extremely rare phenomenon. We report a case of a 67-year-old man who experienced SR of non-small-cell lung cancer (NSCLC), which progressed after fifth-line chemotherapy and regressed after chemotherapy ceased. Surprisingly, the primary tumor size continued to decrease for more than 13 months and his general condition markedly improved after discontinuation of the chemotherapy. To our knowledge, this is the first report of SR in a patient with NSCLC that was not responsive to a fifth round of chemotherapy.