ASCO-GU: PET/CT useful in identifying patients with disseminated seminoma

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PET/CT may help identify patients with disseminated seminoma that was not detected by CT scan, according to a study presented last week at the 2010 Genitourinary Cancers Symposium (ASCO-GU) in San Francisco.

Yohan Loriot, MD, from the Institut Gustave Roussy in Villejuif, France, and colleagues evaluated the utility of FDG-PET to identify occult dissemination in stage I seminoma. After orchiectomy and a signed informed consent, patients with testicular seminoma and no evidence of metastases on CT scan of the pelvis, abdomen and thorax (stage I) underwent a PET/CT, said Loriot. 

The phase II study included 56 patients from March 2004 to June 2008. Eleven percent had a "positive PET/CT, with abnormalities in the retroperitoneum. These six PET-positive patients were treated by either immediate or differed chemotherapy and none relapsed thereafter,” said Loriot.

Among 50 PET-negative patients, seven requested adjuvant chemotherapy and did not relapse, according to Loriot and colleagues.

"Of the remaining 43 PET-negative patients, five relapsed, all in the retroperitoneum, with a delay of six, eight, 10, 16 and 18 months respectively and these patients achieved a continuous disease-free status after radiotherapy or chemotherapy," added Loriot.

The researchers found the two-year relapse rate was 19 percent in PET-negative patients who did not request the adjuvant treatment and the overall survival rate was 100 percent with a median follow-up of 31 months.

Loriot and colleagues concluded that the study confirmed that post-orchiectomy treatment can be avoided in a majority of patients with stage I seminoma and also found that PET/CT helped in identifying about half (six/11) of the patients with disseminated seminoma that was not detected by CT scan.