2368 - Impact of Radiation Therapy on Malignant Rhabdoid Tumor of the Kidney

Purpose/Objective(s): Malignant rhabdoid tumor of the kidney (MRTK) is a rare and aggressive tumor, primarily affecting young children. To effect cure, intensive multimodal treatment is standard and entails chemotherapy, surgery, and radiation therapy (RT). Due to the rarity of the diagnosis, significant challenges exist in determining the impact of RT on patient outcomes. The hypothesis is that radiation therapy is associated with improved overall survival in patients with malignant rhabdoid tumor of the kidney.

Materials/Methods: Patients diagnosed with MRTK from 2004 to 2019 from the National Cancer Database were analyzed. Patients who did not receive surgery or died within 30 days of surgery were excluded. Kaplan-Meier survival analyses were conducted to evaluate overall survival (OS) of the entire cohort, stratified by age, metastatic disease, and RT utilization. Log-rank tests were used to compare survival distributions.

Results: The cohort included a total of 132 patients. Median age was <1 (range <1 to 16, IQR: 1.0 year). 64 patients presented with metastatic disease at diagnosis. 72 patients received RT. One and three-year overall survival of the entire cohort was 50% and 39%, respectively. Patients aged <1 year exhibited significantly worse 3-year OS compared to those aged =1 year (23% vs. 61%, p<0.0001). Metastatic disease was associated with worse OS compared to localized disease (20% vs. 58%, p<0.0001). RT was associated with improved OS across the cohort; those who received RT demonstrated significantly better 3-year OS than those who did not receive RT (56% vs. 19%, p<0.0001). In non-metastatic cases, there was a trend toward improved OS in patients who received RT to primary site compared to no RT (71% vs 47%, p=0.07). Among patients with metastatic disease, RT to the primary tumor was associated with improved survival compared to no RT (44% vs. 9%, p<0.01).

Conclusion: MRTK remains highly fatal in younger children and those burdened with metastatic disease. Radiation therapy is associated with improved overall survival in patients with and without metastatic disease. Table 1: Clinical characteristics of patients with malignant rhabdoid tumor of kidney.