Sensorineural Hearing Loss as a Sequelae of Radiotherapy and Chemotherapy in Head and Neck Cancer - An Observational Study from Maharashtra, India

Abstract

BACKGROUND Radiotherapy is a very well-known treatment modality for head and neck cancers besides surgery. The cochlea and its neuroepithelium are sensitive to ionizing radiation and resultant damage as it remains in the field of irradiation, the chemotherapy also has a similar effect leading to sensorineural hearing loss (SNHL). To minimize the adverse effects of hearing the advent of technology like intensitymodulated radiotherapy (IMRT) using smaller doses of radiation is now available with good control of the disease. The intended concomitant uses of chemotherapeutic agent cisplatin for increasing the sensitivity of radiation may induce ototoxicity. Both of these modalities result in a pronounced effect on highfrequency sensorineural hearing loss. We wanted to determine and compare sensorineural hearing loss amongst cases of head and neck cancer treated by radiotherapy, chemotherapy either alone or in a combination of both. METHODS All clinically diagnosed patients of head and neck cancer requiring treatment using radiotherapy or chemotherapy alone or in combination having a normal hearing on pure tone audiometry (PTA) were enrolled in the study. All enrolled cases were divided into three groups namely A, B and C based on treatment received like radiotherapy, chemotherapy and combination respectively and their effect on hearing was compared. Hearing acuity was assessed by doing PTA before and after completion of treatment and at 6 months follow up in every case. RESULTS In groups A, B and C SNHL was noted at higher frequencies of 4 kHz and 8 kHz during 1st as well as final follow up. Hearing loss was found maximum in group C receiving combination treatment compared to the other two groups receiving in isolation. Hearing loss was the least in Group - A cases that received radiotherapy using the IMRT technique. CONCLUSIONS The possibility of SNHL is increased in cases receiving a combination of radio and chemotherapy (94 %). Extra care of shielding the cochlea is essentially required during treatment with high doses (> 60Gy) using conformal radiotherapy to limit the resultant radiotherapy-induced SNHL. Radiation-induced SNHL in the IMRT technique was the least (28 %) in the group - A cases and hence should be employed in every case. Future searches for cases of head and neck malignancy the newer effective combination of chemotherapeutic drug and radiation obviating the ototoxicity needs to be continued. KEY WORDS Cisplatin, Radiotherapy, Intensity - Modulated, Audiometry, Pure - Tone, Ototoxicity, Hearing Loss, Sensorineural