Volumetric assessment of lymph node metastases in patients with non-seminomatous germ cell tumors treated with chemotherapy

Introduction: We evaluate volumetry and RECIST (Response Evaluation Criteria In Solid Tumors) as methodologies for response after chemotherapy for non-seminomatous germ cell tumour with retroperitoneal lymph node metastases.Methods: We performed a retrospective analysis of non-seminomatous testicular tumours and concurrent retroperitoneal lymph node metastases, which received chemotherapy and had computed tomography scans before and after treatment. Volumetric analysis and RECIST criteria were used to calculate response rates. We included a new category (favourable response) for patients with response rates between 70%. We calculated the correlation between volumetric and RECIST criteria with histological and clinical variables.Results: In total, 18 patients met the inclusion criteria. Histopathologic analysis of orchiectomy showed teratoma in 55.5% of patients, and those without teratoma had predominantly embryonal carcinoma. The mean baseline volume of retroperitoneal metastases was 447 cc, the mean post-chemotherapy volume was 33.6 cc, and the response rate was 62.6%. According to RECIST criteria, the mean baseline diameter was 4.93 cm, the mean post-chemotherapy diameter was 2.39 cm, and the response rate was 42.4%. Large post-chemotherapy residual masses correlated in both classifications with teratoma. The response rate was associated with the need for surgical treatment and the volumetric classification correlated with the need for lymphadenectomy.Conclusions: This study evaluated volumetry as a way to measure clinical response in lymph node metastases of non-seminomatous germ cell tumours. Volumetric analysis is the next step in the evaluation of response rate; its accuracy remains to be determined. Teratoma had greater residual masses and our classification correlated with the need for lymphadenectomy.