Chemosensitivity of lung cancer: Differences between the primary lesion and lymph node metastasis

In this study, chemosensitivity tests were performed on both primary lesions (PLs) and lymph node metastases (LMs) from surgically resected non-small cell lung cancer (NSCLC). Differences between the results obtained were evaluated. Operative specimens were obtained from 13 patients with NSCLC [6 with squamous cell carcinoma (SQ) and 7 with adenocarcinoma (AD)] whose lymph nodes were confirmed to be positive for metastasis. Both the PL and LM from the same patient were examined immediately after resection. The collagen gel droplet-embedded culture drug sensitivity test (CD-DST) was used as the chemosensitivity test against six anticancer drugs [5-fluorouracil (5-FU), cisplatin, gemcitabine, docetaxel, vinorelbine and SN-38 (an active metabolite of irinotecan)]. When the growth rate, determined by the T/C ratio (T, signal for viable cells in the treated group and C, signal in the control) was less than 50%, the tumor cells were considered to be sensitive to the drug. Only in 4 cases (2 SQ and 2 AD) was the chemosensitivity of the primary lesion identical to that of LM. In the SQ cases, chemosensitivity of the primary lesions to 5-FU tended to be consistent with that of LMs. In contrast, the primary lesions in 4 of the 7 AD cases were negative for chemosensitivity to 5-FU; however, LMs were sensitive. In many cases, the chemosensitivity of the PLs to each anticancer drug differed from that of the LMs. In conclusion, both primary and metastatic tumors should be examined to ensure maximum clinical efficacy of in vitro drug-sensitivity testing for adjuvant chemotherapy after complete resection of n1 and n2 NSCLC.