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TOPLINE:

In patients with locally advanced cervical cancer receiving chemoradiation, irradiating less than whole uterus led to a low local recurrence rate and less radiation to the bowel but significantly higher locoregional recurrence. 

METHODOLOGY:

• Guidelines for treatment of locally advanced cervical cancer with intensity modulated radiation therapy (IMRT) recommend including the entire uterus in the clinical target volume; however, this approach is debated.
• At a single institution, researchers developed a more individualized clinical target volume based on the tumor volume that involved the cervix and accounted for organ movement when the bladder was full or empty to decrease radiation to the surrounding bowel. They then added a 5 mm margin to form the final planning target volume, which did not necessarily include the entire uterus.
• The researchers identified 109 patients (median age, 57 years) with locally advanced cervical cancer (International Federation of Gynecology and Obstetrics 2018 stage IB-IVA), who received concurrent chemoradiation therapy following this method between 2011 and 2022.
• Patients underwent external beam radiation therapy using IMRT at a dose of 48.6 Gy delivered in 27 fractions, followed by a boost to 54.0-61.9 Gy targeting the involved lymph nodes. Subsequently, patients received high-dose-rate brachytherapy boost to 27.5-30.0 Gy, employing 5.5-7.0 Gy per fraction. Overall, 53 patients had ≥ 75% of the uterus included in the planning target volume, and 56 had < 75% included.
• The researchers assessed 2-year cumulative incidence of local recurrence, locoregional recurrence, and distant metastasis.

TAKEAWAY:

• The 2-year cumulative incidence for all patients of local recurrence, locoregional recurrence, and distant metastasis was 4.2%, 12.3%, and 16.1%, respectively.
• In patients with ≥ 75% of the uterus included in the final planning target volume, the 2-year cumulative incidence of locoregional recurrence was significantly lower than in patients with < 75% of the uterus included (6.5% vs 18%; P = .01).
• The 2-year cumulative incidence of local recurrence for the ≥ 75% group was lower but not significantly so compared with the under 75% group (1.9% vs 6.4%). However, the ≥ 75% group also received a significantly higher dose of radiation to the bowel than those with less uterus included (P = .02).
• The 2-year overall survival was 88% for the entire cohort, and 2-year progression free survival was 77.9%.
• Overall, 1 patient (0.9%) experienced acute grade ≥ 3 gastrointestinal toxicities, and 2 patients (1.8%) experienced late grade ≥ 3 genitourinary toxicities.

IN PRACTICE:

Overall, treating a smaller proportion of the uterus (< 75%) was associated with higher overall rates of local and locoregional recurrence, but the authors concluded that "patients achieved excellent local control with < 1% of isolated uterine failures with low toxicities."

"Less than whole uterus irradiation could be considered for carefully selected cervix cancer patients to decrease bowel dose and possible treatment-related toxicity," the team added.

SOURCE:

This work was led by Caressa Hui from Stanford University and published online on March 2, 2024, in Radiotherapy and Oncology.

LIMITATIONS:

The retrospective study design introduced inherent biases. The patient cohort spanned over a decade, making it heterogeneous. A small number of patients lacked an initial staging MRI scan. Retrospective toxicity scoring may have caused underestimation of the actual risk for prospective morbidity. The small sample size and low event numbers limited the power to detect statistically significant differences in outcomes.

DISCLOSURES:

The study funding source was not declared. The authors had no relevant conflicts of interest.