Key words non-small cell lung cancer; dimensional conformal radiotherapy; dose escalation

0 Introduction

    Three-dimensional conformal radiotherapy (3  dimensional conformal radiation therapy, 3DCRT) the biggest advantage is to make tumors was much higher doses than conventional radiation therapy, irradiation of normal tissue around the tumor significantly reduced. In this study, a 3DCRT the clinical stage Ⅰ test aims dose progressively NSCLC patients with the maximum tolerated dose (MTD) and observe radiotherapy acute side effects.

    1 Data and methods

    1.1 Case inclusion criteria Age 18 to 75 years of age; Karnofsky score ≥ 70; weighing nearly 3 months to <10% decline; histologically or cytologically confirmed NSCLC; UICC stage Ⅱ B ~ Ⅲ B in 1997 period (except the N3 period and malignant pleural effusion).

    1.2 Methods since October 2004 to December 2005, a total of 25 patients were included in this project, including the IIB 3 Li, Ⅲ A 16 Li, 6 cases of Ⅲ B, Male 20 Li, female 5 Li, median age 60 years old, squamous cell carcinoma 20 cases, 4 cases of adenocarcinoma, bronchioloalveolar carcinoma.

    1.3 Radiation therapy Radiation therapy points chest back relative to the wild conventional radiotherapy and 3DCRT plus the amount of irradiation in two stages.

    Conventional radiotherapy dose was 40Gy / 4 weeks. 3DCRT plus the amount of the illuminated area to the gross tumor visible on the planning CT. 35% 3组。">Dose escalation method is divided into <25%, 25% to 35%, depending on the receiving ≥ 20 Gy irradiation, the percentage of the total lung volume, lung,> 35% of the 3 groups. Increments each group three weeks, irradiated for 5 days a week: <25% of the group from increments of 2.5 Gy / 3.5 Gy / week increments 0.5 Gy; 25% to 35% of group to 3.0 in increments of 2.5 Gy / 35%从2.25 Gy/次递增至2.75 Gy/次,即每周递增0.25 Gy。">Gy / times weekly increments 0.25 Gy;> 35% from 2.25 Gy / increment to 2.75 Gy / week increments 0.25 Gy.

    2 Results

    2.1 dose level completed, in addition to the 2 patients Ⅲ grade acute radiation pneumonitis termination of irradiation to 81.25 Gy and 77.5 Gy radiotherapy, the remaining 23 patients, according to the radiation treatment planning to complete radiation treatment planning, the highest dose has been increasing up to 85 Gy.

    2.2 acute radiation reaction I, grade II acute radiation esophagitis incidence of 73.9% (17/23), there are cases of grade Ⅲ acute radiation esophagitis (4.3%), I, grade II acute radiation pneumonitis was 60.9% (14/23), Ⅲ grade of 8.6% (2/23).

    2.3 tumor of spot efficacy of CR was 8.6% (2/23), PR rate was 60.9% (14/23), SD rate of 30.4% (7/23), with a total effective rate of 69.6% (19/23). Radioactive incidence of pulmonary fibrosis: Ⅰ to Ⅱ level was 86.9% (20/23). The overall median survival time of 20 months, the 1-year survival rate was 78.3%; 1-year local control rate was 83%; 1-year distant metastasis rate was 30.4%.

    3 Discussion

    3DCRT allows tumors by irradiation of high dose regional concentration, reduce exposure doses of the surrounding normal tissue, and increase the dose can improve the local control rate of NSCLC the, so Wurstbauer, [1] of 85 patients with NSCLC application of three-dimensional conformal radiation therapy technology treatment, tumor dose of 86.1 Gy (80.0 to 94.5 Gy), 1 – and 2-year survival rates were 64% and 32%, respectively. Domestic Wu Kailiang [2] reported NSCLC three-dimensional conformal radiotherapy Clinical I, II Phase I dose increments experiment, 50 cases Ⅱ ~ Ⅲ B NSCLC first conventional fractionated irradiation of 4.2 weeks (42Gy/21) technology, with three-dimensional conformal tumor plus the amount of 3 Gy / total tumor dose escalation levels were 69,72,75 and 78 Gy. Results The overall median survival time of 22 months, 1,2 year survival rates were 70%, 47%. The radiobiology show the process of conventional radiation therapy more than a month, the remnants of the tumor cells will accelerate the emergence of accelerated repopulation, given a higher dose than conventional radiation therapy, and then be able to inhibit tumor cell proliferation, tumor cells proliferation. Head and neck cancer and esophageal accelerated repopulation appeared in 3 to 4 weeks after radiation therapy, in view of the NSCLC same for tumors of epithelial origin, speculated that the NSCLC accelerated repopulation may also appear in the late conventional radiation therapy, the subject of inhibit accelerated repopulation by post-process dose incrementally improve the split dose, to achieve the purpose to improve local tumor control rate, overall median survival time of 20 months, the highest increment reached 85Gy dose, MTD has not yet obtained the treatment of recent results make encouraging, radiation late toxicity and long-term effect needs further observation.