From the Journals

Anomalous RT dose linked to lower survival in uterine cancer



As many as one in eight patients with uterine cancer who undergo adjuvant radiation therapy may have been treated with doses that are inconsistent with standard practice, a new study suggests.

Writing in JCO Clinical Cancer Informatics, Corbin D. Jacobs, MD, of Duke University, Durham, N.C., and coauthors analyzed National Cancer Database data from 14,298 women with stage IIIC1-C2 uterine cancer who underwent adjuvant radiation therapy after hysterectomy. The analysis included information on radiation therapy site, modality, dose, fractions, timing, duration, and stage, as well as details about the facilities at which the treatment was given.

Overall, 16% of the women had at least one ‘anomalous’ entry in their records of radiation therapy. The most common anomalies were that the combined total radiation therapy dose was insufficient, or there was an insufficient number of external beam radiation therapy fractions, both of which may have represented an incomplete course of radiation therapy.

Other anomalies were excessive brachytherapy fractions, inconsistency in the staging, and less than 100 days of radiation therapy.

The study showed that the 5-year overall survival rate in individuals who had at least one anomalous data entry was 51.3% compared with 58% among individuals without any anomalous entries (P less than .001). The difference in survival rates was entirely accounted for by insufficient, excessive, or unknown radiation therapy dose.

More than half of patients in the study had missing or unknown data for at least one entry, and this was associated with lower 5-year survival compared with patients with complete data entries.

The researchers also looked at facility-specific factors, such as the type of facility, its location, and its distance from the patient’s home, and how these impacted the frequency of anomalous data. They found that comprehensive community cancer programs had the lowest incidence of anomalous data (14.7%) compared with non–comprehensive community cancer programs, which had an incidence of 17.1%.

The incidence of anomalous data was highest in facilities in the south Atlantic, east south central and west south central regions of the United States. The further away from a patient’s home the reporting facility was, the higher the presence of anomalous data.

“Because an insufficient RT dose or fewer than 20 fractions accounted for such a large proportion of the anomalies, patients may potentially be more likely to have an incomplete RT course or complete RT in a hypofractionated manner when the facility is farther from their home,” the authors wrote.

One author was an employee of Bioventus, and three declared research funding from the pharmaceutical sector. No other conflicts of interest were declared.

SOURCE: Jacobs C et al. JCO Clin Cancer Inform. 2019, May 3. doi: 10.1200/CCI.18.00118.

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