Hypothyroïdie après traitement radiochirurgical des cancers de l'hypopharynx

Hypothyroïdie après irradiation cervicale dans le traitement des cancers du nasopharynx et du sein : étude prospective à propos de 84 patients

PURPOSE

1/ To evaluate the incidence of hypothyroidism following radiotherapy in the management of breast and nasopharyngeal carcinomas, 2/ to define the role of a systematic post therapeutic screening.

PATIENTS AND METHODS

From January 1996 through March 2001 a systematic evaluation of the clinical and the biological thyroid function was performed on a cohort of 84 patients that received supraclavicular irradiation. Selected patients had either a mammary (37 cases) or a nasopharyngeal (47 cases) carcinoma. Initial work up included thyroid inspection and palpation, and biological tests: serum FT4 and TSH levels, radioimmunochemistry, completed by dynamic thyroid stimulation, using TRH, in case of border line low T4 or isolated high TSH levels. Tests were repeated every three months the first year, and then every six months. Replacement therapy with L Thyroxin was administered in case of hypothyroidism.

RESULTS

All selected patients had a normal function initially. With a mean two years follow up (1-5 years), 24 patients (29%) experienced hypothyroidism, half of whom (13 cases) being purely biological. Five patients (11%), with a nasopharyngeal carcinoma, presented also with associated pituitary failure. Clinical symptoms were minor or mild in all cases. Hypothyroidism was detected at a mean 21 months follow up. In 2 patients, hypothyroidism disappeared spontaneously within 6 months. Possible predictive factors were evaluated: age of the time of radiation, gender, percentage of irradiated thyroid, total dose, dose per fraction, tumour type and chemotherapy. Only age appeared significantly correlated with thyroid dysfunction (range: 10-30 years, P=0.002).

CONCLUSION

Hypothyroidism is a frequent and certainly underestimated complication following radiotherapy of the neck. In such patients, a systematic clinical and biological evaluation every three months the first year, and then every six months until five years is recommended.

Endoscopic sinus surgery in previously irradiated patients

PURPOSE

Our purpose was to evaluate the safety and efficacy of endoscopic sinus surgery in irradiated patients with absolute indications for sinus surgery.

PATIENTS AND METHODS

During 5 years at a tertiary referral center, more than 200 patients received irradiation to a field that included the paranasal sinuses. Complaints related to the sinuses are common in such patients and often include crusting and increased mucus drainage. Six patients presented with significant sinus infections in the absence of tumor recurrence and failed medical management. Additional problems included epiphora and nasal obstruction caused by cicatricial choanal stricture. Surgical interventions included ethmoidectomy, multiple osteotomies, debridement of scarred or devitalized tissue, and dacryocystorhinostomy. Outcome measures included intraoperative findings and complications, length of hospital stays, endoscopic assessments of the healing over 6 months post-operatively, and improvement or persistence of symptoms over 2 to 3 years of follow-up.

RESULTS

Surgery can be technically difficult because of derangements of normal anatomy and dehiscence of important structures. Although bleeding problems, prolonged admission, and delayed healing were noted in certain cases, they did not result in long-term morbidity.

CONCLUSIONS

Endoscopic sinus surgery has become an invaluable tool in the treatment of refractory sinusitis. Our literature review has revealed no information, however, regarding endoscopic sinus surgery in previously irradiated patients. Theoretically, such patients are at risk for healing problems and anatomic derangements, which could lead to complications. There is, nevertheless, a theoretical benefit to avoiding external approaches in patients who might heal poorly.

[Late effects of ionizing radiations on the thyroid gland]

The thyroid is the purest endocrine gland in the body and is likely to produce clinically significant abnormalities after external radiotherapy. Functional clinical modifications after direct irradiation exceeding 30 Gy are essentially related to hypothyroidism which may be clinically overt or subclinical with normal serum free thyroxine levels and high thyrotropin concentrations; the risk of hyperthyroidism, silent thyroiditis and Hashimoto's disease is also increased. Secondary hypothyroidism related to irradiation of the hypothalamus and the pituitary gland may arise with doses over 40-50 Gy following treatment for brain and nasopharyngeal tumors--Morphological glandular modifications induced by radiotherapy are responsible for the appearance of benign adenomas, more rarely cystic degenerations and specially well differentiated papillary or follicular carcinomas among children and adults. After irradiation during childhood for benign or malignant tumors, thyroid cancers are more frequent, higher for younger children, and the relative excess risk is increased from 15.6-to 53-fold; tumors can belatedly occur, more than 35 years after initial therapy. Thereby, in order to limit excess morbidity, it is evident that long term supervision with careful clinical and biological evaluations is necessary for patients who previously received neck, upper mediastinum and pituitary radiation therapy.