| Objective:(1) To compare the dose distribution between thethree-dimensional conformal radiotherapy plan (3D-CRT) with late courseboost to the primary tumor (Boost plan)and the3D-CRT plan without latecourse boost to the primary tumor (Conventional plan) in N0patients withthoracic esophageal carcinoma.(2) To retrospectively study the prognosis andits prognostic factors of N0thoracic esophageal carcinoma treated with3D-CRT following late course boost to the primary tumor.Methods:1. Dosimetric results: Six N0thoracic esophageal carcinomapatients treated with3D-CRT were collected. The target volume and organs atrisk (OARs) were delineated on the treatment planning system. The GTV wasdefined as any visible tumor on the image. The CTV was defined as the GTVplus a3.0-cm margin superior and inferior to the primary tumor and a0.8-cmradial margin. The PTV was defined as the CTV plus a1.0-cm longitudinalmargin and a0.5-cm radial margin. The PTV1was defined as GTV plus a1.5cm margin superior and inferior to the primary tumor and a0.8cm radialmargin. The prescribed dose to PTV was5000cGy in5weeks followed by1400cGy/7fractions boost to PTV1in the boost plan. The prescribed dose toPTV was6000cGy in6weeks in the conventional group. The two plans wereevaluated by dose distribution of the targets and OARs such as lungs, spinalcord and heart.2. Clinical observation of129patients with N0thoracicesophageal carcinoma were treated by3D-CRT from January2006toDecember2009. The patients were grouped into two groups according to latecourse boost to the primary tumor or not. The prescribed dose to PTV was5000cGy in5weeks followed by1000-1400cGy to PTV1in the boost group. The prescribed dose to PTV was5800-6400cGy in5.5-6.5weeks in theconventional group. The toxicities, tumor response, overall survivval andlocoregional control were observed. The acute radiation toxicities such asradiation pneumonitis, radiation esophagitis and leukocytopenia were gradedaccording to RTOG radiation scoring criteria.Results:1. The mean lung dose, V5, V10, V13, V30except V20werelower the boost plan than those in conventional plan (P＜0.05). The maximumdose of spinal cord was similar in the two plans. Comparing with theconventional plan, the boost plan was lower in the V50and mean dose ofheart (P＜0.05). The GTVD90and GTVD95of boost plans were6548.0±82.156cGy vs6265.67±134.667cGy (P=0.001) and6509.5±69.333cGy vs6211.67±139.827cGy (P=0.001) respectively,282.33±87.79cGy and297.83±104.08cGy respectively higher than those of CFR plans.2. Clinicalobservation:(1) Tumor response: The complete response (CR), partialresponse (PR) and no response (NR) were31.8%(41/129),65.9%(85/129)and2.3%(3/129) in this group. The total response rate was97.7%(126/129).The tumor response rates were96.9%and98.4%in the boost group andconventional group respectively (P=0.543).(2) Overall survival: The1-,2-and3-year survival rates for all the patients in this study were81.1%,54.2%and42.5%respectively, The1-,2-and3-year survival rates of the boost groupand conventional group were79.0%,53.7%,48.0%and83.1%,54.6%,37.1%respectively. The median survival was17months and16.5months in the twogroups. No statistical difference was found in the two groups (P=0.434). The1-,2-and3-year survival rates of patients with tumor length of≤5.5cm or＞5.5cm were88.1%,64.7%,55.5%and73.3%,42.5%,28.0%(P=0.002). The1-,2-and3-year survival rates of patients in stage I, stage II and stage IIIwere88.9%,68.9%,62.9%;94.1%,60.7%,50.3%and57.5%,32.5%,11.3%(P=0.000). The1-,2-and3-year survival rates of patients with CR orPR were89.9%,77.0%,62.7%and78.7%,44.0%,34.2%(P=0.018). In Coxmultivariate analysis, clinical stage and tumor response were independentfactors for the overall survival.(3) Local control: The1-,2-and3-year locoregional control rates of this group were69.3%,49.3%and41.2%respectively. The1-,2-and3-year locoregional control rates of the boostgroup and conventional group were65.3%,50.8%,46.2%and72.9%,48.0%,36.2%respectively (P=0.497). The1-,2-and3-year locoregional control ratesof the patients with tumor length of≤5.5cm or＞5.5cm were79.1%,58.1%,50.1%and57.6%,42.5%,29.7%(P=0.034). The1-,2-and3-year localcontrol of patients in stage I, stage II and stage III were77.3%,68.4%,58.5%;94.1%,52.5%,43.7%and42.8%,25.7%,15.2%(P=0.000). The1-,2-and3-year local control rates of patients with CR or PR were79.6%,68.9%,53.5%and65.5%,40.0%,35.9%(P=0.017). The Cox multivariate analysisshowed that clinical stage was an independent factor for the local control.(4)Toxicities: The radiation esophagitis rate in the boost group and conventionalgroup was78.5%and79.7%respectively. The symptomatic radiationpneumonitis was26.2%and31.3%respectively (P=0.861).(5) The totalfailure rate was59.9%(76/129). The failure rate was63.1%(41/65) and54.7%(35/64) respectively in the boost group and conventional group. And thelocoregional failure rate was40.0%(26/65) and34.4%(22/64) respectively inthe two groups. Distant metastasis was18.5%(12/65) and14.1%(9/64)respectively. No significant difference was found between the twogroups(P=0.880).Conclusion:1. The plan of three-dimensional conformal radiotherapywith late course boost to the primary tumor in N0patients with thoracicesophageal carcinoma conferred higher dose coverage for tumor target andlower dose for lung, spinal cord, esophagus and heart.2. The late course boosttechnique for N0patients with thoracic esophageal carcinoma didn't decreasethe tumor response, overall survival, local control and didn't increase theradiation esophagitis, pneumonitis and blood toxicities.3. Clinical stage andtumor response were the independent factors for overall survival and Clinicalstage was an the independent factor for local control in N0patients.4. Localfailure or uncontrol was the main reason for No patients.Conclusion:(1) Conformal radiotherapy with elective nodal irradiation for thoracic esophageal SCC showed no significant advantage over theconformal radiotherapy with the involved nodal irradiation in overall survival,locoregional control and progression-free survival.(2) Conformalradiotherapy with elective nodal irradiation conferred a higher radiationpneumonitis compared to conformal radiotherapy with involved nodalirradiation.(3) Dose to lungs and spinal cord was higher with elective nodalirradiation than that with involved nodal irradiation.(4) Lower regional lymphnode failures in patients with esophageal carcinoma treated with radiotherapyis related to the incidental dose to regional nodal stations without intentionalelective nodal irradiation (ENI).(5) Volume of GTV before radiotherapy andshort-term efficacy were independent factors for overall survival, GTVvolume before radiotherapy was the independent factor for locoregionalcontrol rate. |
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