A new risk stratification model can identify patients with stage I seminoma who have a high risk of relapse, according to research presented at the 2023 ASCO Genitourinary Cancers Symposium.
The new model — which includes tumor size in 3 categories, Rete testis invasion, and lymphovascular invasion — outperformed the traditional risk stratification model, said study presenter Robert Hamilton, MD, of University Health Network in Toronto, Canada.
To create the model, Dr Hamilton and colleagues evaluated 1016 patients with unilateral, clinical stage I seminoma. All patients were under active surveillance and had normal serum tumor marker levels post-orchiectomy.
The patients’ median age at baseline was 36 years. Their median tumor size was 32 mm, 61% of patients had germ cell neoplasia in situ, 37% had Rete testis invasion, 12% had lymphovascular invasion, and 10% had multifocality.
At a median follow-up of 7.7 years, 14.7% of patients had relapsed. Most (97%) relapses occurred in retroperitoneal nodes. Treatment for relapse included radiation (54%) and chemotherapy (46%). There were 11 deaths. None were related to seminoma, and 1 was related to treatment.
A multivariate analysis showed significant associations between relapse-free survival (RFS) and the following factors:
- Rete testis invasion (hazard ratio [HR], 1.93; 95% CI, 1.36-2.72; P <.001)
- Having a primary tumor measuring 2-5 cm (HR, 2.06; 95% CI, 1.25-3.40; P =.005) or larger than 5 cm (HR, 3.14; 95% CI, 1.79-5.50; P <.001).
There was a trend toward an association between RFS and lymphovascular invasion as well (HR, 1.48; 95% CI, 0.97-2.25; P =.066).
The researchers used these features — primary tumor size (>5 cm or 2-5 cm vs <2 cm), Rete testis invasion, and lymphovascular invasion — to formulate the new predictive model.
The researchers compared the new model with the traditional model, which includes primary tumor size (>4 cm vs ≤4 cm) and Rete testis invasion. The new model outperformed the traditional model for predicting RFS (C-index, 0.65 and 0.61, respectively).
Using the new model, 56.4% of patients in this cohort were categorized as having a very low risk of relapse, 41.3% were categorized as low risk, and 2.3% were categorized as high risk. The risk of relapse at 5 years was 8% in the very low-risk group, 20% in the low-risk group, and 44% in the high-risk group.
“[W]e were able to identify an admittedly small subset, 3% of the cohort, that were at increased risk of relapse,” Dr Hamilton said. “This may introduce the concept of talking about adjuvant therapies and a shared decision-making model with these patients.”
Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Boormans J, Sylvester RJ, Anson-Cartwright L. European Association of Urology (EAU) Testicular Cancer Guidelines Panel: A new prognostic factor risk group classification for patients with clinical stage 1 seminoma in active surveillance. ASCO GU 2023. February 16-18, 2023. Abstract 410.
This article originally appeared on Cancer Therapy Advisor