Abstract
We investigated the rectal dose-sparing effect and tumor control of a point A dose-reduced plan in patients with Stage I–II cervical cancer (≤4 cm) arising from a small-sized uterus. Between October 2008 and August 2011, 19 patients with Stage I–II cervical cancer (≤4 cm) were treated with external beam radiotherapy (EBRT) for the pelvis and CT-guided brachytherapy. Seven patients were treated with brachytherapy with standard loading of source-dwell positions and a fraction dose of 6 Gy at point A (conventional brachy-plan). The other 12 patients with a small uterus close to the rectum or small intestine were treated with brachytherapy with a point A dose-reduction to match D2cc of the rectum and <6 Gy as the dose constraint (‘point A dose-reduced plan’) instead of the 6-Gy plan at point A (‘tentative 6-Gy plan’). The total doses from EBRT and brachytherapy were added up and normalized to a biological equivalent dose of 2 Gy per fraction (EQD2). The median doses to the high-risk clinical target volume (HR-CTV) D90 in the conventional brachy-plan, tentative 6-Gy plan and point A dose-reduced plan were 62 GyEQD2, 80 GyEQD2 and 64 GyEQD2, respectively. The median doses of rectal D2cc in the corresponding three plans were 42 GyEQD2, 62 GyEQD2 and 51 GyEQD2, respectively. With a median follow-up period of 35 months, three patients developed Grade-1 late rectal complications and no patients developed local recurrence. Our preliminary results suggested that CT-guided brachytherapy using an individualized point A dose-reduced plan might be useful for reducing late rectal complications while maintaining primary tumor control.
Highlights
Stage IB1–IIA2 cervical cancer can be cured by radiation therapy (RT) or surgery with similar effectiveness, but the rates and types of complications differ between the modalities [1]
The present study was conducted to evaluate the potential benefit of dose adaptation at image-guided brachytherapy (IGBT) for non-bulky cervical cancer arising from a small-sized uterus
Treatment planning was done so as to reduce the rectal doses within acceptable levels while maintaining tumor control in patients with Stage I–II cervical cancer (≤4 cm) arising from a small-sized uterus treated with computed tomography (CT)-based brachytherapy
Summary
Stage IB1–IIA2 cervical cancer can be cured by radiation therapy (RT) or surgery with similar effectiveness, but the rates and types of complications differ between the modalities [1]. With radical hysterectomy and pelvic lymphadenectomy, the most common adverse effects are lymphedema and urinary complications [2], whereas with RT the major sites of complications are the rectum, bladder and small bowel [3]. In Japan, the standardized treatment protocol for non-bulky (≤4 cm) Stage I and II cervical cancer is whole pelvic external beam radiation therapy (EBRT) of 20 Gy in 10 fractions, followed by pelvic EBRT with center shields of 30 Gy in 15 fractions and high-dose-rate intracavitary brachytherapy (HDR-ICBT) of 24 Gy in four fractions at point A [3]. The rates of late complications of Grade 1 or 2 were reported as 18% in the rectosigmoid colon, 0% in the bladder, and 4% in the small intestine [3]
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