| IntroductionEsophageal cancer was a common malignant tumor with high morbidity in our country and did great harm to peopled health. Irradiation treatment of esophageal cancer was one of major treatment ways, but no obvious progress had been made. Uncontrol of primary site and local recurrence were the important failure factors of irradiation treatment. Some reported that local failure rate was 70 - 85% , and 5 -year survival rate was only 10% or so. In order to look for the best treatment way and improve the local control rate and survival rate, scholars did a lot of research on altering time - dose - fraction factor (TDF) and had made progress. During the period from Oct 2000 to Feb 2002, 34 patients with esophageal cancer who were divided into two groups equally received irregular and conventional external fractionated irradiation treatment.Materials34 esophageal carcinoma patients who hadnt been treated by any method before were collected, with Karnofsky score5= 70 and ability to swallow fluid food. All patients were proved to be squamous cell carcinoma with pathological confirmation.According to the result of esophageal barium meal, all patients were equally divided into two groups based on the length and the siteof the lesion, one was irregular fractionated irradiation group, the other was conventional fractionated ( CF) irradiation group. Clinical computed tomography (CT) stage was adopted, which was put forward by Moss in 1981.All patients were treated by PRIMUS medical linear accelerator, MEVASIN simulator and MEVAPLAN treatment plan system.MethodsAll patients were set front A field and back B. C two fields. In irregular fractionated irradiation group, patients were given 500cGy on every Friday through front A field, then had a rest for two days, from Monday to Thursday, patients were give 150cGy every day through B and C field alternatively, the total tumor dose (Dt) was 6950cGy given 30 times for45 -49 days. In CF group, from Monday to Friday,alternative irradiation through one field was performed every day with a dose of 200cGy, after two days rest, such irradiation was repeated, Dt was 7000cGy given 35 times for 49 - 54 days.Patients in two groups with supraclavicular lymph node metastasis had their supraclavicular area irradiated with Dt VOcGy. For the patients of upper and low thoracic esophageal cancer, their supraclavicular area and left gastrici lymph node area were given preventional irradiation with 40Gy respectively if they hadnt lymph node metastasis in these two areas.ResultsAccording to Barium meal check and CT, the curative effect of irregular fractionated irradiation group was better than that of conventional fractionated irradiation group, and so was the clinical symptomimprovement. Acute irradiation reactions such as irradiation esophagi-tis, radiation bronchitis and leukocytopenia were similar in both groups.DiscussionIrregular Fractionated Irradiation could act on the hypoxic cells more effectively than conventional method which caused tumor recurrence. Some treatment was defeated because of 10-50% hypoxic cells which were resistant to ray in human solid tumor. Through research on tumor cell reproduction cycle, some scholars found that most hypoxic cell were in G0 phase, and the cells in the cycle were in good oxygenated conditions, hypoxia could inhibit DNA starting of earlier S phase, indicating the accumulation of cells in G, phase and disturbing the reproduction process. When cells were reoxygenated, DNA could restore in a few minutes, and when cells were hypoxic, hypoxia could produce more radioresistant genes and led to increase the resistance to radiation.Local uncontrol and local recurrence were the major factors which led to treatment failure. In order to raise the curative rate and reduce the resistance to ray, irregular fractionated irradiation was adopted, that was big single dose and many small doses were combined.Radiobiological foundation of irregular fractionated irradiation was that 95% carcinoma oxygenated cells wer...
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