Clinical outcomes of de novo versus relapsed early metastatic testicular seminoma treated with contemporary radiation therapy.

Chemotherapy (CHT) or radiation therapy (RT) are first line treatments for clinical stage II testicular seminoma (CS-II). Historically, clinical stage I (CS-I) seminoma was also treated with CHT or RT, but in the past two decades practice has shifted towards active surveillance for CS-Iwith RT or CHT reserved for patients with progression to CS-II. Limited data exist on contemporary RT techniques and patient stratification, i.e. de novo (CS-II at orchiectomy) vs. relapsed (CS-II diagnosed during surveillance after orchiectomy for CS I). We investigated outcomes in CS-II patients treated with RT in the modern era across two institutions.

A retrospective review identified 73 patients treated with RT for CS-II A or B seminoma between 2001-2022. Recurrence free survival (RFS) was calculated by the Kaplan-Meier method and univariate analyses were performed with Log-Rank or Cox proportional hazard regression. Recurrence was defined as biopsy-proven metastatic seminoma after RT completion. Second malignancies were defined as a biopsy-proven malignancy originating in the prior RT field.

Thirty-eight (52%) patients presented with de novo CS-II while 35 (48%) patients had relapsed CS-II. Median follow-up was 4.8 years (IQR: 2.3 - 8.1). Five-year RFS was 82% overall (92% in relapsed patients and 73% in de novo patients). Relapsed CS-II disease had lower recurrence rates following RT compared to de novo CS-II disease. All recurrences occurred outside the prior RT field and were salvaged. Disease-specific survival was 100%. Two second malignancies occurred (prostate, colorectal cancer at 67 months and 119 months post-RT, respectively).

In patients with CS-II seminoma treated with modern RT, there were no in-field recurrences. Presentation with de novo CS-II is associated with out-of-field recurrence. Subject to further larger-scale validation, our results suggest that compared to CS-II at time of relapse, de novo CS-II may portend more aggressive or micrometastatic disease beyond the retroperitoneum, raising the possibility of benefit from chemotherapy after radiation.

International journal of radiation oncology, biology, physics. 2023 Sep 15 [Epub ahead of print]

Daniel B Rosen, Anushka Ghosh, Andrzej Niemierko, Clair J Beard, Praful Ravi, Alok Tewari, Christopher Sweeney, Richard J Lee, Philip Saylor, Neil Martin, Jason A Efstathiou, Kent Mouw, Sophia C Kamran

Harvard Radiation Oncology Program, Boston, MA. Electronic address: ., Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA., Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA. Electronic address: ., Department of Radiation Oncology, Brigham and Women's Hospital, Boston, MA., Dana Farber Cancer Institute, Boston, MA., South Australian Immunogenomics Cancer Institute, University of Adelaide, Adelaide, SA, Australia., Harvard Medical School, Boston, MA; Division of Hematology-Oncology, Massachusetts General Hospital, Boston, MA., Harvard Medical School, Boston, MA; MGH Cancer Center, Department of Medicine, Massachusetts General Hospital., Department of Radiation Oncology, Brigham and Women's Hospital, Boston, MA; Dana Farber Cancer Institute, Boston, MA; Harvard Medical School, Boston, MA., Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA; Harvard Medical School, Boston, MA., Department of Radiation Oncology, Brigham and Women's Hospital, Boston, MA; Dana Farber Cancer Institute, Boston, MA; Harvard Medical School, Boston, MA; Broad Institute of MIT and Harvard, Cambridge, MA., Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA; Harvard Medical School, Boston, MA; Broad Institute of MIT and Harvard, Cambridge, MA. Electronic address: .