Stromberg J S, Martinez A A, Horwitz E M, Gustafson G S, Gonzalez J A, Spencer W F, Brabbins D S, Dmuchowski C F, Hollander J B, Vicini F A
Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan 48073, USA.
Cancer J Sci Am. 1997 Nov-Dec;3(6):346-52.
Prostate-specific antigen levels are used to judge disease control of prostate cancer. No published data attest to the greater ability of conformal brachytherapy to control disease compared with conventional radiation at a single institution. This report compares the biochemical response rates in patients with stages T2b to T3c prostate cancer treated with conformal brachytherapy boost and external beam radiation with the rates in patients treated with conventional external radiation alone.
From November 1991 through November 1995, 58 patients received 45.6 Gy pelvic external irradiation and three high dose rate iridium-192 conformal boost implants of 5.5 to 6.5 Gy each. They were compared with 278 similarly staged patients treated from January 1987 through December 1991 with external beam radiation to prostate-only fields (median dose 66.6 Gy). No patient received androgen deprivation. Patient outcome was analyzed for biochemical control. Biochemical failure was defined as a prostate-specific antigen level > 1.5 ng/mL and rising on two consecutive values. If serial posttreatment prostate-specific antigen levels were showing a continuous downward trend, failure was not scored.
Median follow-up was 43 months for the conventionally treated group and 26 months for the brachytherapy boost group. The median pretreatment prostate-specific antigen level was 14.3 ng/mL for the external-beam-radiation-alone group and 14.0 ng/mL for the brachytherapy boost group. The median Gleason scores were 6 and 7, respectively, for the two groups. The biochemical control rate was significantly higher in the brachytherapy boost treatment group. Three-year actuarial biochemical control rates were 85% versus 52% for the conformally and conventionally treated patients, respectively. In a multivariate analysis, the use of conformal brachytherapy boost and pretreatment prostate-specific antigen level were significant prognostic determinants of biochemical control. The 3-year actuarial rates of biochemical control for conformally versus conventionally treated patients, respectively, were 83% versus 72% for a pretreatment prostate-specific antigen level of 4.1 to 10.0 ng/mL, 85% versus 47% for a prostate-specific antigen level of 10.1 to 20.0 ng/mL, and 89% versus 29% for prostate-specific antigen > 20 ng/mL. When the analysis was limited to patients in both groups with a minimum 12-month follow-up, the brachytherapy boost group continued to show a higher biochemical control rate compared with the conventional radiation group (3-year actuarial rates of 86% vs 53%).
These preliminary results show a significant improvement in the biochemical response rate with conformal boost brachytherapy and pelvic external radiation compared with conventional radiation alone. These results, coupled with our previously reported acceptable toxicity rates, support the use of this technique.
前列腺特异性抗原水平用于判断前列腺癌的疾病控制情况。尚无已发表的数据证明在单一机构中，适形近距离放疗与传统放疗相比在控制疾病方面具有更强的能力。本报告比较了接受适形近距离放疗加量和外照射治疗的T2b至T3c期前列腺癌患者的生化反应率与仅接受传统外照射治疗的患者的生化反应率。
1991年11月至1995年11月，58例患者接受了45.6 Gy的盆腔外照射以及三次高剂量率铱-192适形加量植入，每次植入剂量为5.5至6.5 Gy。将他们与1987年1月至1991年12月接受仅前列腺区域外照射（中位剂量66.6 Gy）的278例分期相似的患者进行比较。没有患者接受雄激素剥夺治疗。分析患者的生化控制情况以评估治疗结果。生化失败定义为前列腺特异性抗原水平>1.5 ng/mL且连续两次测量值上升。如果治疗后连续的前列腺特异性抗原水平呈持续下降趋势，则不计为失败。
传统治疗组的中位随访时间为43个月，近距离放疗加量组为26个月。单纯外照射组的中位治疗前前列腺特异性抗原水平为14.3 ng/mL，近距离放疗加量组为14.0 ng/mL。两组的中位 Gleason评分分别为6分和7分。近距离放疗加量治疗组的生化控制率显著更高。适形治疗和传统治疗患者的三年精算生化控制率分别为85%和52%。在多因素分析中，使用适形近距离放疗加量和治疗前前列腺特异性抗原水平是生化控制的重要预后决定因素。对于治疗前前列腺特异性抗原水平为4.1至10.0 ng/mL的患者，适形治疗和传统治疗患者的三年精算生化控制率分别为83%和72%；对于前列腺特异性抗原水平为10.1至20.0 ng/mL的患者，分别为85%和47%；对于前列腺特异性抗原>20 ng/mL的患者，分别为89%和29%。当分析仅限于两组中随访至少12个月的患者时，近距离放疗加量组的生化控制率仍高于传统放疗组（三年精算率分别为86%和53%）。
这些初步结果表明，与单纯传统放疗相比，适形加量近距离放疗和盆腔外照射在生化反应率方面有显著改善。这些结果，再加上我们之前报告的可接受的毒性率，支持了该技术的应用。
