Prospective Validation of a High Dimensional Shape Model for Organ Motion in Intact Cervical Cancer

Outcomes from a 3-fraction high-dose-rate brachytherapy regimen for patients with cervical cancer

PURPOSE

To estimate local control, survival, and toxicity associated with a 3-fraction (3F) image-guided brachytherapy (IGBT) regimen compared to longer fraction (LF) for cervical cancer.

METHODS

150 patients treated between 2015-2020 with 3F (24Gy in 3 fractions) or LF (28...30 Gy in 4-5 fractions) were reviewed. The primary outcome was 2-year local failure. We compared overall survival (OS), disease-free survival (DFS), hospitalizations, and toxicity.

RESULTS

There were 32 patients in the 3F group and 118 in the LF group, with a median follow up of 22 months. The 3F had worse performance status (p = 0.01) but otherwise similar characteristics. The 2-year local failure rate was 3.6% (95% CI 0%, 10.6%) for 3F, and 7.5% (95% CI 2.4%, 12.6%) for LF. The univariable hazard ratio (HR) for local failure for 3F was 0.43 (0.05, 3.43; p = 0.43). Moreover, 2 of 32 (6.3%) 3F patients experienced Grade ...3 toxicity compared to 7 of 118 (5.9%) LF patients (p = 1.0), with no difference in hospitalization within 2 years (p = 0.66) and no treatment-related deaths.

CONCLUSIONS

Local control was excellent, with long term survival and toxicity similar between the groups. These findings support consideration of 3F.

Disparities in time to start of definitive radiation treatment for patients with locally advanced cervical cancer

BACKGROUND

Chemoradiation or radiation therapy alone are curative standards for patients with locally advanced cervical cancer.

OBJECTIVE

To investigate factors that influence time to initiation of chemoradiation or radiation and the subsequent impact of time to treatment on recurrence and survival outcomes.

METHODS

Patients with locally advanced cervical cancer treated with definitive chemoradiation or radiation at our institution between November 2015 and August 2020 were retrospectively identified. Time to treatment initiation was defined as the number of days from date of diagnosis (via biopsy) to the start date of radiation. The cohort was stratified by the median time to treatment into early (<75 days) and delayed (≥75 days) cohorts. Multivariable logistic regression was conducted to examine factors associated with delayed time to treatment.

RESULTS

We identified 143 patients with locally advanced cervical cancer who underwent definitive chemoradiation or radiation. Median follow-up time was 18 months (range 2-62). A total of 71 (49.7%) patients had time to treatment <75 days and 72 (50.3%) patients had time to treatment ≥75 days. The delayed cohort had a higher proportion of Hispanic patients (51.4% vs 31.0%, p=0.04). In multivariable modeling, Hispanic women were 2.71 times more likely (p=0.04) to undergo delayed time to treatment than non-Hispanic white women. Additionally, patients with stage >IIB disease were less likely to undergo delayed time to treatment (OR 0.26, p=0.02) than patients with stage

CONCLUSION

Hispanic patients with locally advanced cervical cancer were more likely to receive delayed time to definitive treatment of ≥75 days. Further studies examining the presence of similar disparities in delay to definitive treatment for locally advanced cervical cancer at other institutions and settings are warranted.

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Key Words

• COVID-19
• Cervical Cancer
• Radiation

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MESH Headings

• Adenocarcinoma/pathology
• Carcinoma, Squamous Cell/pathology
• Chemoradiotherapy
• Female
• Humans
• Neoplasm Staging
• Retrospective Studies
• Uterine Cervical Neoplasms/radiotherapy

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Affiliation(s)

Nikhil V Kotha Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California, USA
Casey W Williamson Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California, USA
Loren K Mell Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California, USA
James D Murphy Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California, USA
Elena Martinez University of California San Diego Moores Cancer Center, La Jolla, California, USA
Pratibha S Binder Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego, La Jolla, California, USA
Jyoti S Mayadev Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California, USA

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Advances in External Beam Radiation Therapy and Brachytherapy for Cervical Cancer

The standard of care for the definitive treatment of locoregionally advanced cervical cancer is external beam radiation therapy (EBRT) with concurrent chemotherapy followed by a brachytherapy boost. Historically, EBRT was delivered via a two-dimensional technique based primarily on bony landmarks. This gave way to three-dimensional conformal radiation therapy, which allows for dose calculation and adjustment based on individual tumour and patient anatomy. Further technological advances have established intensity-modulated radiation therapy (IMRT) as a standard treatment modality, given the ability to maintain tumoricidal doses to target volumes while reducing unwanted radiation dose to nearby critical structures, thereby reducing toxicity. Routine image guidance allows for increased confidence in patient alignment prior to treatment, and the ability to visualise the daily position of the targets and organs at risk has been instrumental in allowing safe reductions in treated volumes. Additional EBRT technologies, including proton therapy and stereotactic body radiation therapy, may further improve the therapeutic index. In the realm of brachytherapy, a shift from point-based dose planning to image-guided brachytherapy has been associated with improved local control and reduced toxicity, with additional refinement ongoing. Here we will discuss these advances, the supporting data and future directions.

The Potential Value of MRI in External-Beam Radiotherapy for Cervical Cancer

The reference standard treatment for cervical cancer is concurrent chemoradiotherapy followed by magnetic resonance imaging (MRI)-guided brachytherapy. Improvements in brachytherapy have increased local control rates, but late toxicity remains high with rates of 11% grade ≥3. The primary clinical target volume (CTV) for external-beam radiotherapy includes the cervix and uterus, which can show significant inter-fraction motion. This means that generous margins are required to cover the primary CTV, increasing the radiation dose to organs at risk and, therefore, toxicity. A number of image-guided radiotherapy techniques (IGRT) have been developed, but motion can be random and difficult to predict prior to treatment. In light of the development of integrated MRI linear accelerators, this review discusses the potential value of MRI in external-beam radiotherapy. Current solutions for managing pelvic organ motion are reviewed, including the potential for online adaptive radiotherapy. The impacts of the use of MRI in tumour delineation and in the delivery of stereotactic ablative body radiotherapy (SABR) are highlighted. The potential role and challenges of using multi parametric MRI to guide radiotherapy are also discussed.

Problems and solutions in IGRT for cervical cancer

The contribution of Image-guided Radiotherapy (IGRT) to modern radiotherapy is undeniable, being the way to bring into daily practice the dosimetric benefits of Intensity-Modulated Radiotherapy (IMRT). Organ and target motion is constant and unpredictable at the pelvis, thus posing a challenge to the safe execution of IMRT. There are potential benefits of IMRT in the radical treatment of cervical cancer patients, both in terms of dose escalation and decrease of toxicity. But it is essential to find IGRT solutions to control the aspects that can lead to geographic miss targeting or organs at risk (OAR) overdose. This review seeks to describe the problems and possible solutions in the clinical implementation of IMRT/IGRT protocols to treat intact cervical cancer patients.