Small cell lung cancer that satisfies one or more of the following conditions: 1) BRCA1 or BRCA2 mutation, ATM deficiency, MRE11A mutation 2) Mutation of other HR(homologous recombination) pathway genes: BLM, NBN, RAD50, RAD52, RAD54L, RAD51, RAD51B, RAD51C, RAD51D, RECQL, RECQL4, RECQL5, RPA1, WRN etc.