BOSTON—In patients with stage II testicular seminoma treated with radiotherapy, relapse in the irradiated site appears to be uncommon, according to a new long-term study presented at the American Society for Radiation Oncology annual meeting.

The retrospective study, which included 52 men, also suggests that infradiaphragmatic radiotherapy alone may be associated with a significant risk of mediastinal/supraclavicular (MSCV) failure, particularly in patients with stage IIB disease.

The investigators, led by Christopher Hallemeier, MD, a resident in radiation/oncology at Mayo Clinic in Rochester, Minn., found that most major cardiac events and secondary malignancy events occurred more than 20 years after radiotherapy. This finding highlights the importance of vigilant long-term follow-up, the researchers noted. In addition, the study showed that stage II testicular seminoma treated with radiotherapy is associated with excellent cause-specific survival.

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“Radiation treatment is an effective treatment for patients with stage II testicular seminoma, but we did see [that] 19% of patients had a cardiac event after the radiotherapy,” Dr. Hallemeier said. “It is unclear if radiation is causative, but we do know that these patients are at a slight higher risk for cardiac events.”

Following radiotherapy, major cardiac events occurred in 10 patients at a median of 18 years (range 7-30 years) and secondary malignancies occurred in five patients (10%) at a median of 27 years (range 20-34 years).

The 52 patients received treatment from 1974 to 2007. Of these, 48 patients (92%) had computed tomography (CT) staging. The investigators determined overall survival (OS), relapse-free survival (RFS), and cause-specific survival (CSS). They defined major cardiac events as myocardial infarction, coronary artery bypass grafting or stenting, or valve replacement. The investigators defined a second malignancy as a biopsy-confirmed malignancy occurring in the radiotherapy field.

The median patient age at the time of diagnosis was 36 years (range 22-71 years). Twenty-four patients had stage IIA, seven had stage IIB, and 17 had IIC disease; four patients were listed as having stage II disease, but a more specific classification was not available.

The median infradiaphragmatic radiotherapy dose was 30.7 Gy and 26 patients received prophylactic MSCV radiotherapy with a median dose of 20.5 Gy.  Four patients with bulky nodal disease also received chemotherapy. Of these patients, one had stage IIB and three had stage IIC.

“Our median follow up was 19 years,” Dr. Hallemeier told Renal & Urology News. “That is a long follow-up, and it is clinically significant in showing that the results are durable and it allowed us to look for late morbidity from the radiation. Second malignancies tended to come late after the treatment, so we think that patients who are treated with radiation and cured need to be followed long-term to monitor and detect any late complications from the radiation in treatment, such as cardiac events or secondary malignancies.”

The estimated OS was 94% and 81% at 10 and 20 years, respectively, Dr. Hallemeier said. The estimated CSS was 96% and 96%. The RFS at 10 years was 83% and 54% for stage IIA and IIB patients, respectively. The RFS was 81% for patients with stage IIC and 100% for patients listed as having stage II and not otherwise specified. Ten patients (19%) experienced disease relapse. Of these, relapse occurred in the MSCV region of seven patients, the para-aortic lymph nodes in one patient, the lung in one patients, and the peritoneal cavity in one patient. Eight patients underwent successful salvage chemotherapy and/or surgery. Two died of seminoma. The patients receiving prophylactic MSCV radiotherapy  had a lower relapse rate in the MSCV region (one of 26) compared with those who did not receive prophylaxis (six of 26).