Functional MRI-guided Bone Marrow-sparing Intensity Modulated Radiotherapy for Pelvic Malignancies

Outcomes for Patients With Cervical Cancer Treated With Extended-Field Intensity-Modulated Radiation Therapy and Concurrent Cisplatin

Objective

To evaluate disease outcomes and toxicity in patients with cervical cancer treated with extended-field intensity-modulated radiotherapy.

Materials and Methods

We included all patients treated with extended-field intensity-modulated radiotherapy and concurrent weekly cisplatin from 2003 to 2010 at 2 institutions. Overall survival and disease-free survival were estimated using Kaplan-Meier method. Locoregional failure (LRF), distant failure, and competing mortality were calculated using cumulative incidence functions. Acute and late toxicity were graded using Common Terminology Criteria for Adverse Events (CTCAE) and Radiation Therapy Oncology Group late radiation morbidity scoring criteria, respectively.

Results

The study included 21 patients, 14 and 20 of which had positive para-aortic and pelvic nodes, respectively. The median follow-up was 22 months. Eighteen-month overall survival and disease-free survival were 59.7% (95% confidence interval [CI], 41.2%–86.4%) and 42.9% (95% CI, 26.2%–70.2%). Eighteen-month cumulative incidences of LRF, distant failure, and competing mortality were 9.5% (95% CI, 1.5–26.8%), 42.9% (95% CI, 21.3–62.9%), and 4.8% (95% CI, 0.3–20.2%), respectively. Eighteen-month cumulative incidences of late grade 3 or higher-grade genitourinary and gastrointestinal toxicity were 4.8% (95% CI, 0.2%–20.3%) and 0%, respectively.

Conclusions

Intensity-modulated extended-field radiotherapy was associated with low rates of late toxicity and LRF. High rates of distant failure indicate that this group of patients could benefit from intensified systemic therapy.

Impact of bone marrow radiation dose on acute hematologic toxicity in cervical cancer: principal component analysis on high dimensional data

PURPOSE

To study the effects of increasing pelvic bone marrow (BM) radiation dose on acute hematologic toxicity in patients undergoing chemoradiotherapy, using a novel modeling approach to preserve the local spatial dose information.

METHODS AND MATERIALS

The study included 37 cervical cancer patients treated with concurrent weekly cisplatin and pelvic radiation therapy. The white blood cell count nadir during treatment was used as the indicator for acute hematologic toxicity. Pelvic BM radiation dose distributions were standardized across patients by registering the pelvic BM volumes to a common template, followed by dose remapping using deformable image registration, resulting in a dose array. Principal component (PC) analysis was applied to the dose array, and the significant eigenvectors were identified by linear regression on the PCs. The coefficients for PC regression and significant eigenvectors were represented in three dimensions to identify critical BM subregions where dose accumulation is associated with hematologic toxicity.

RESULTS

We identified five PCs associated with acute hematologic toxicity. PC analysis regression modeling explained a high proportion of the variation in acute hematologicity (adjusted R(2), 0.49). Three-dimensional rendering of a linear combination of the significant eigenvectors revealed patterns consistent with anatomical distributions of hematopoietically active BM.

CONCLUSIONS

We have developed a novel approach that preserves spatial dose information to model effects of radiation dose on toxicity, which may be useful in optimizing radiation techniques to avoid critical subregions of normal tissues. Further validation of this approach in a large cohort is ongoing.