impact of lymphoceles on organ at risk doses in patients undergoing adjuvant pelvic radiation for carcinoma cervix

Purpose: Lymphoceles form part of target volume during adjuvant radiation for cervical cancer. The impact of lymphocele on doses to adjacent organs at risk (OAR) has not been studied. The present study was designed to investigate the same.

Methods: From January 2011- December 2013 all patients were evaluated for presence of postoperative lymphocele. Planned target volume (PTV) was generated with and without lymphocele volume. Intensity modulated radiation therapy (IMRT) plans were generated and dose to OARs was determined. The impact of lymphocele volume on OAR dose was determined by Spearman rank test and Wilcoxon sign rank sum test was performed to determine the impact of lymphocele on OAR dose.

Results: A total of 11/93 patients had postoperative lymphoceles. Of these 63% were located in internal iliac region. The median lymphocele volume at simulation was 42.8 cc (range 6.4-105cc) and remained almost stable at 44 cc (range 3-100 cc) at fifth week of radiation. Negative correlation was observed between mean lymphocele volume and dose to bladder, rectum and bowel bag. Presence of lymphocele led to reduction in V30 and V40 of bladder (84 cc vs 77 cc, p = 0.004; 68 cc vs 63 cc; p = 0.01) and rectum (87 cc vs 80 cc, p = 0.0001; 73.5 cc vs 65 cc, p = 0.01) and V15 of bowel bag (843 cc vs 804 cc; p = 0.01).

Conclusion: Presence of lymphoceles displaced OARs leading to reduction in high dose volumes of rectum and bladder.