Lee Nancy, Xia Ping, Fischbein Nancy J, Akazawa Pam, Akazawa Clayton, Quivey Jeanne M
Department of Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA, USA.
Int J Radiat Oncol Biol Phys. 2003 Sep 1;57(1):49-60. doi: 10.1016/s0360-3016(03)00405-x.
To review the University of California-San Francisco (UCSF) experience of using intensity-modulated radiation therapy (IMRT) to treat head-and-neck cancer focusing on the importance of target volume delineation and adequate target volume coverage.
Between April 1995 and January 2002, 150 histologically confirmed patients underwent IMRT for their head-and-neck cancer at our institution. Sites included were nasopharynx 86, oropharynx 22, paranasal sinus 22, thyroid 6, oral tongue 3, nasal cavity 2, salivary 2, larynx 2, hypopharynx 1, lacrimal gland 1, skin 1, temporal bone 1, and trachea 1. One hundred seven patients were treated definitively with IMRT +/- concurrent platinum chemotherapy (92/107), whereas 43 patients underwent gross surgical resection followed by postoperative IMRT +/- concurrent platinum chemotherapy (15/43). IMRT was delivered using three different techniques: 1) manually cut partial transmission blocks, 2) computer-controlled auto-sequencing segmental multileaf collimator, and 3) sequential tomotherapy using dynamic multivane intensity-modulating collimator. Forty-two patients were treated with a forward plan, 102 patients with an inverse plan, and 6 patients with both forward and inverse plans. The gross target volume (GTV) was defined as tumor detected on physical examination or imaging studies. In postoperative cases, the GTV was defined as the preoperative gross tumor volume. The clinical target volume (CTV) included all potential areas at risk for microscopic tumor involvement by either direct extension or nodal spread including a margin for patient motion and setup errors. The average prescription doses to the GTV were 70 Gy and 66 Gy for the primary and the postoperative cases, respectively. The site of recurrence was determined by the diagnostic neuroradiologist to be either within the GTV or the CTV volume by comparison of the treatment planning computed tomography with posttreatment imaging studies.
For the primary definitive cases with a median follow-up of 25 months (range 6 to 78 months), 4 patients failed in the GTV. The 2- and 3-year local freedom from progression (LFFP) rates were 97% and 95%. With a median follow-up of 17 months (range 8 to 56 months), 7 patients failed in the postoperative setting. The 2-year LFFP rate was 83%. For the primary group, the average maximum, mean, and minimum doses delivered were 80 Gy, 74 Gy, 56 Gy to the GTV, and 80 Gy, 69 Gy, 33 Gy to the CTV. An average of only 3% of the GTV and 3% of the CTV received less than 95% of the prescribed dose. For the postoperative group, the average maximum, mean, and minimum doses delivered were 79 Gy, 71 Gy, 37 Gy to the GTV and 79 Gy, 66 Gy, 21 Gy to the CTV. An average of only 6% of the GTV and 6% of the CTV received less than 95% of the prescribed dose.
Accurate target volume delineation in IMRT treatment for head-and-neck cancer is essential. Our multidisciplinary approach in target volume definition resulted in few recurrences with excellent LFFP rates and no marginal failures. Higher treatment failure rates were noted in the postoperative setting in which lower doses were prescribed. Potential dose escalation studies may further improve the local control rates in the postoperative setting.
回顾加利福尼亚大学旧金山分校（UCSF）使用调强放射治疗（IMRT）治疗头颈癌的经验，重点关注靶区勾画的重要性和靶区的充分覆盖。
1995年4月至2002年1月期间，150例经组织学确诊的头颈癌患者在本机构接受IMRT治疗。治疗部位包括鼻咽癌86例、口咽癌22例、鼻窦癌22例、甲状腺癌6例、舌癌3例、鼻腔癌2例、唾液腺癌2例、喉癌2例、下咽癌1例、泪腺癌1例、皮肤癌1例、颞骨癌1例、气管癌1例。107例患者接受IMRT根治性治疗并联合或不联合铂类同步化疗（92/107），43例患者接受手术大体切除，术后行IMRT联合或不联合铂类同步化疗（15/43）。IMRT采用三种不同技术实施：1）手动切割部分透射挡块；2）计算机控制的自动序列节段多叶准直器；3）使用动态多叶调强准直器的断层放疗。42例患者采用正向计划治疗，102例患者采用逆向计划治疗，6例患者同时采用正向和逆向计划治疗。大体肿瘤靶区（GTV）定义为体格检查或影像学检查发现的肿瘤。术后病例中，GTV定义为术前大体肿瘤体积。临床靶区（CTV）包括所有因直接蔓延或淋巴结转移而有微小肿瘤累及风险的潜在区域，包括患者运动和摆位误差的边界。GTV的平均处方剂量，原发病例为70 Gy，术后病例为66 Gy。通过将治疗计划CT与治疗后影像学检查进行比较，由诊断神经放射科医生确定复发部位是在GTV还是CTV范围内。
对于中位随访时间为25个月（范围6至78个月）的原发根治性病例，4例患者GTV出现复发。2年和3年局部无进展生存率（LFFP）分别为97%和95%。中位随访时间为17个月（范围8至56个月）时，7例患者在术后出现复发。2年LFFP率为83%。对于原发组，GTV的平均最大剂量、平均剂量和最小剂量分别为80 Gy、74 Gy、56 Gy，CTV分别为80 Gy、69 Gy、33 Gy。平均仅有3%的GTV和3%的CTV接受的剂量低于处方剂量的95%。对于术后组，GTV的平均最大剂量、平均剂量和最小剂量分别为79 Gy、71 Gy、37 Gy，CTV分别为79 Gy、66 Gy、21 Gy。平均仅有6%的GTV和6%的CTV接受的剂量低于处方剂量的95%。
在头颈癌IMRT治疗中，准确的靶区勾画至关重要。我们在靶区定义方面的多学科方法导致复发较少，LFFP率优异且无边缘复发。术后设定中处方剂量较低时，治疗失败率较高。潜在的剂量递增研究可能进一步提高术后设定中的局部控制率。
