Multiple regression analysis of the quality of life for patients with nasopharyngeal carcinoma after radiotherapy

The purpose of this study is to evaluate the effects of time interval, the severity of the disease and personal characteristic variables upon quality of life (QoL) for patients with nasopharyngeal carcinoma after radiotherapy. Three hundred and thirty-two with nasopharyngeal carcinoma patients treated by conventional radiotherapy technique in two institutions were invited to participate; all received not less than 70 Gy to nasopharynx and not less than 50 Gy to neck. The mean irradiation dosage to nasopharynx and neck were 70.69 ± 2.49 Gy and 60.25 ± 6.88 Gy, respectively. Health- related quality of life was assessed 3 months or later after completion of radiotherapy (the mean follow up period ranged from 3 to 360 months, the mean follow up period: 52.85 ± 61.78 months) by means of the European Organization for Research and Treatment of Cancer (EORTC) Core Quality of Life Questionnaire (QLQ C-30) and the EORTC head and neck cancer-specific questionnaire (QLQ H&N-35). After completion of radiotherapy, the periods for patients to fill in the questionnaire were divided into 4 groups: 3-6 months, 6-12 months, 1-5 years and more than 5 years. In addition, the severity of the diseases was divided into early and late stages. By multiple regression analysis, the "time interval" was the most important factor of the QoL. The next was "family income". Besides, the severity of disease and the other personal characteristic variables affected the different degrees for the different items of the QoL. The factors of affecting global QoL were the time interval (invert U curve) and family income. As a whole, time interval and family income were the most important factors to affect the QoL. In respect of time interval, most items of QoL were improved 6 months after completion of radiotherapy and stablized in the long term. Higher family income showed the better QoL. Our study provided clinical physicians the assessement of the risk for treatment, rehabilitation after treatment, mental consultation and supportive care. It was also helpful for us to understand the QoL for patients with nasopharyngeal carcinoma after radiotherapy.