ERBB2 and small cell lung carcinoma: HER2 expression was higher in CDDP‐resistant SCLC cells than in parental cells, and the antitumor effect of HER2‐targeting NIR‐PIT was higher in CDDP‐resistant SCLC, suggesting the HER2 expression level was positively correlated with the efficacy of NIR‐PIT.