(P005) Time to Cervical Stent Placement as a Predictor of Prolonged Treatment Course in Patients Treated With Definitive Chemoradiation Therapy for Cervical Cancer

Mark A. Zaki, MD, Michael M. Dominello, DO, Erin J. McSpadden, MPH, Robert T. Morris, MD, Steven R. Miller, MD; Department of Radiation Oncology, Wayne State University School of Medicine/Detroit Medical Center; Department of Gynecologic Oncology, Department of Radiation Oncology, Karmanos Cancer Center

Background: While it is known that definitive chemoradiotherapy (CRT) for cervical cancer should be completed within 56 days, many patients experience delays which prolong treatment. At many institutions, a cervical stent is inserted 1 or more days prior to start of high-dose–rate brachytherapy (HDR), though optimal time of placement is unknown. Placement early on, as the cervix is responding to therapy, may compromise the positioning of the stent, suture integrity, and dosimetry at the time of brachytherapy, whereas late placement may prolong overall treatment length. Our objective is to evaluate factors predictive of prolonged treatment time, including time of stent placement, in this patient population.

Methods: After institutional review board (IRB) approval, 71 consecutive patients treated from 2008 to 2013 for cervical cancer with CRT followed by HDR were identified. Medical records were reviewed to gather demographic, clinical, and treatment data. Prolonged treatment was defined as > 56 days per the American Brachytherapy Society guidelines. In addition to the time of stent placement, the following variables were evaluated using paired t-tests and univariate logistic regression: age, race, use of intensity-modulated radiation therapy (IMRT) vs conventional technique, time to first HDR, genitourinary (GU) or gastrointestinal (GI) toxicity, and the presence of a boost.

Results: Median age was 50 years. Thirty-nine percent of patients had International Federation of Gynecology and Obstetrics (FIGO) stage I disease, 39% had stage II, 16% had stage III, and 6% had stage IV. Median external beam radiation therapy (EBRT) dose was 45 Gy with a 5.4-Gy sidewall or parametrial boost. The median HDR dose was 27.5 Gy in five fractions. Sixty-six percent was treated with a four-field technique, and 34% was treated using IMRT. Sixty-eight women had HDR with a ring and tandem applicator, whereas three underwent an interstitial implant. For the 68 patients requiring a cervical stent, the median time from start of EBRT to cervical stent placement and first HDR was 29 and 38 days, respectively. The median treatment length for all patients was 59 days. Factors associated with prolonged treatment were time to cervical stent placement (P = .001), delay ≥ 2 days between final EBRT and initial HDR (P = .0195), any grade GU toxicity (P = .0007) or GI toxicity (P = .0002), and the presence of a boost (P = .0006). Age, stage, and IMRT vs conventional technique were not significantly associated with prolonged treatment time. Excluding patients with any treatment breaks, the following factors remained associated with prolonged treatment: time to cervical stent placement, with a mean of 31 days vs 27 days in patients completing treatment in ≤ 56 days (P =.05), and time to initial HDR (mean, 47 vs 34 days; P = .01).

Conclusion: In this series of patients, acute toxicity, increased time to cervical stent placement, and time to first HDR treatment were associated with prolonged treatment time. Patients who completed treatment in ≤ 56 days had a lower average time to cervical stent placement, 27 vs 31 days. Preventing and treating acute toxicity in order to minimize treatment breaks remains essential. Additionally, our results suggest that cervical stent placement during the fourth week of treatment is also an important factor in facilitating timely completion of treatment.