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Whole-lung radiation may not be necessary in favorable histology Wilms' tumor responders
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CHICAGO — The elimination of radiation therapy may be feasible in children with favorable histology Wilms’ tumor who achieve a complete response of their lung metastases with initial chemotherapy, according to findings presented at the ASCO Annual Meeting.
These findings may spare certain patients the long-term toxicities associated with lung radiation, according to the researchers.
David B. Dix, MD, a physician at the British Columbia Children’s Hospital in Vancouver, presented the initial results of the National Wilms’ Tumor Study-5, which included patients with stage IV favorable histology Wilms’ Tumor who received vincristine/dactinomycin/doxorubicin (DD4A) and whole-lung irradiation.
“We see that there are generally favorable outcomes for these patients, but that’s not the whole story,” Dix said. “Survivors are at significant risk for late effects.”
The researchers hypothesized that patients with a complete response of their lung nodules after 6 weeks of chemotherapy would achieve an acceptable EFS without radiation.
“The null hypothesis was that 4-year EFS for complete response when treated with DD4A therapy and pulmonary radiation is 85%,” Dix said. “Review of the literature suggests that there is justification for the elimination of lung radiation therapy.”
Patient accrual occurred between February 2007 and February 2013.
The analysis included 391 patients, of whom 296 had lung-only metastases. A complete pulmonary response occurred in 105 of those patients.
At the interim analysis, Dix and colleagues observed 20 events in the complete response group — which included 19 recurrences and one second malignancy — which was non-significantly higher than the 14.5 events expected under the null hypothesis.
Two patients died during a median follow-up duration of 2.3 years after recurrence.
The distribution of recurrences showed that 17 occurred in the lung, while one each occurred in the liver and abdomen.
Researchers reported a 78% (95% CI, 68-86%) 4-year EFS rate among patients with a complete pulmonary response.
“However, this is not statistically significantly different from the null hypothesis of 85%,” Dix said.
The 4-year OS was 95% (95% CI, 83-98%).
“We feel that these results compare favorably with NWTS-5 results [Dome JS, et al. J Clin Oncol. 2005;doi:10.1200/JCO.2005.04.7852.] for stage IV favorable histology Wilms’ tumor where all stage IV patients with pulmonary metastases received lung radiation,” Dix said. “This new approach will have a significant effect in reducing the late-effects experienced by these patients down the road.”
Dix raised the question of whether 6 weeks is the optimal cutoff point for defining pulmonary complete response. He added that the Children’s Oncology Group renal tumor committee endorses this approach. – by Rob Volansky
For more information:
Dix DB, et al. Abstract 10011. Presented at: ASCO Annual Meeting; May 29-June 2, 2015; Chicago.
Disclosure: Dix reports no relevant financial disclosures. Please see the abstract for a list of all other researchers’ relevant financial disclosures.