Wong James R, Gao Zhanrong, Merrick Scott, Wilson Paula, Uematsu Minoru, Woo Kevin, Cheng Chee-Wai
Department of Radiation Oncology, The Carol G Simon Cancer Center, Morristown Memorial Hospital, Morristown, NJ 07962, USA.
Int J Radiat Oncol Biol Phys. 2009 Sep 1;75(1):49-55. doi: 10.1016/j.ijrobp.2008.07.049. Epub 2008 Dec 10.
Recent clinical outcome studies on prostate cancer have reported the influence of patient's obesity on the biochemical failure rates after various treatment modalities. In this study, we investigated the effect of patient's physical characteristics on prostate shift in external beam radiotherapy (EBRT) and hypothesized that there maybe a correlation between patient physique and tumor shift.
A retrospective analysis was performed using data for 117 patients who received image-guided radiation therapy (IGRT) for prostate cancer between January 2005 and April 2007. A total of 1,465 CT scans were analyzed. The standard deviations (SDs) of prostate shifts for all patients, along with patient weight, body mass index (BMI), and subcutaneous adipose-tissue thickness (SAT), were determined. Spearman rank correlation analysis was performed.
Of the 117 patients, 26.5% were considered normal weight, 48.7% were overweight, 17.9% were mildly obese, and 6.9% were moderately to severely obese. Notably 1.3%, 1.5%, 2.0%, and 21.2% of the respective shifts were greater than 10 mm in the left-right (LR) direction for the four patient groups, whereas in the anterior-posterior direction the shifts are 18.2%, 12.6%, 6.7%, and 21.0%, respectively. Strong correlations were observed between SAT, BMI, patient weight, and SDs of daily shifts in the LR direction (p < 0.01).
The strong correlation between obesity and shift indicates that without image-guided radiation therapy, the target volume (prostate with or without seminal vesicles) may not receive the intended dose for patients who are moderate to severely obese. This may explain the higher recurrence rate with conventional external beam radiation therapy.
近期关于前列腺癌的临床疗效研究报告了患者肥胖对各种治疗方式后生化失败率的影响。在本研究中，我们调查了患者身体特征对体外放射治疗（EBRT）中前列腺移位的影响，并假设患者体型与肿瘤移位之间可能存在相关性。
对2005年1月至2007年4月期间接受前列腺癌图像引导放射治疗（IGRT）的117例患者的数据进行回顾性分析。共分析了1465次CT扫描。确定了所有患者前列腺移位的标准差（SD），以及患者体重、体重指数（BMI）和皮下脂肪组织厚度（SAT）。进行了Spearman等级相关分析。
117例患者中，26.5%被认为体重正常，48.7%超重，17.9%轻度肥胖，6.9%中度至重度肥胖。值得注意的是，在左右（LR）方向上，四个患者组各自移位大于10 mm的比例分别为1.3%、1.5%、2.0%和21.2%，而在前后方向上，移位比例分别为18.2%、12.6%、6.7%和21.0%。在SAT、BMI、患者体重与LR方向每日移位的标准差之间观察到强相关性（p < 0.01）。
肥胖与移位之间的强相关性表明，对于中度至重度肥胖患者，如果没有图像引导放射治疗，靶区（有或无精囊的前列腺）可能无法接受预期剂量。这可能解释了传统体外放射治疗较高的复发率。
