Effects of bladder status on cervical cancer treatment with intensity‐modulated radiation therapy plans

Abstract

AbstractObjectiveThe present study aimed to compare the effects of different bladder statuses on cervical cancer treatment with intensity‐modulated radiation therapy (IMRT) plans.MethodsA total of 21 cervical cancer patients who were willing to be treated with IMRT in the prone position at the Third Affiliated Hospital of Kunming Medical University from December 1, 2014 to October 31, 2015 were selected for this study. IMRT treatment plans were carried out using computed tomography images of the full and empty bladder. Data were collected to compare the differences between clinical target volume, planning target volume, and the percentage of irradiated volume of the bladder, small bowel, rectum, and caput femoris in patients with full and empty bladders.ResultsClinical target volume, planning target volume, and the volume of organs at risk did not show obvious differences (P > 0.05 in all respects) in patients with different bladder statuses. The average radiation dose of the small bowel of a patient with a full bladder (2056.7 ± 364.7 cGy) was significantly lower than that of a patient with an empty bladder (2319.5 ± 451.58 cGy), P < 0.001. The average radiation dose of the rectum of a patient with a full bladder (4663.7 ± 68.94 cGy) was higher than that of a patient with an empty bladder (4621.6 ± 54.86 cGy), P = 0.039. The percentages of irradiated volume covered by the 5–45 Gy isodose curve (V5–V45) of the small bowel were lower in the full bladder patients than in the empty bladder patients (P < 0.001 in all respects), whereas the percentages of irradiated volume covered by the 45 Gy isodose curve (V45) of the rectum were higher in the full bladder patients (P < 0.05). If a patient had lymphatic metastasis, the V45 irradiated volume ratio (IVR) of the small bowel of a patient with a full bladder was lower than that of a patient with an empty bladder, P < 0.001, whereas the V45 IVR of the rectum increased (P = 0.04). For patients without lymphatic metastasis, the V45 IVR of the small bowel and bladder both decreased with a full bladder compared with an empty bladder (P = 0.002 and 0.01, respectively), and there was no difference in the V45 IVR of the rectum (P = 0.275).ConclusionsIMRT plans delivered to patients with a full bladder in the prone position can reduce the percentage of irradiated volume in the small bowel. For patients with lymphatic metastasis, although keeping a full bladder reduces the percentage of irradiated volume in the intestine, it also increases the percentage of irradiated volume in the rectum