Chemotherapy in Head and Neck Malignancies
Introduction:
Chemotherapy can be used alone or in combinaion with other modalities of treatment. Majority of the head and neck malignancies are squamous cell cancers and the drugs that have been found effective are methotrexate, cisplatin, bleomycin and 5-fluoroucil. Adriamycin has been used for some nonsquamous carcinomas i.e adenoidcystic carcinoma. Dacarbazine is preferred for melanomas. Lymphomas of head and neck are also treated by chemotherapy because these tumors are multifocal in origin and widespread in their involvement.
Types of chemotherapy:
Palliative chemotherapy:
Cytotoxic drugs, singly or in combination are used to treat advanced, recurrent, metastatic disease with the aim of relieving the symptoms and to prolong the life in some of them.
Induction / anterior chemotherapy:
When chemotherapy drugs are used before surgery or irradiation, it is known as induction / anterior chemotherapy. This process helps in reducing the tumour burden and micrometastasis that can occur at the time of surgery or in the period before radiation.
Concurrent chemotherapy:
In this type chemotherapy is used simultaneously with radiotherapy, and it acts as a radiosensitizer to cells which are otherwise radioresistant.
Posterior chemotherapy:
Here chemotherapy is used after surgery / radiation. This therapy aims to cure micrometastasis.
Single agent Vs Multidrug combination therapy:
Methotrexate, cisplatin, bleomycin and 5-flurouracil have been used as single agents and in various dosage forms. They have also been used in combination with other drugs with the object to improve overall response rate and duration of the response. A combination of two or more drugs improves the response rate and definitely improves the quality of patient's life. It has ofcourse failed to improve the duration of the response.
Investigations that needs to be done before starting chemotherapy:
Hematological tests:
Hb% TC/DC Platelet count
These tests serve as a baseline as many of chemotherapeutic agents are myelosuppressive in nature.
Complete urine examination
Biochemical tests:
Blood urea nitrogen Creatinine LFT
Methotrexate and cisplatin are nephrotoxic
Radiology:
X-ray chest (Bleomycin causes interstitial pulmonary fibrosis)
ECG - (for Adriamycin)
Audiogram (cisplatin causes high frequency hearing loss)
CT/MRI - To assess the extent of the disease
Pulmonary function tests: (for Bleomycin)
Nutritional status
Toxicity of chemotherapeutic agents:
Most of these drugs act on rapidly dividing cellls and hence even normal cess like that of hair follicles, GI mucosa and bone marrow are also affected. This could lead to alopecia, stomatitis, nausea, vomiting, diarrhoea, anaemia, leukopenia and thrombocytopenia. Some of these agents are nephrotoxic (methotreate, cistplatin), neurotoxic (vincristine and cisplatin), cardiotoxicity (adriamycin) and bladder toxicity (cyclophosphamide).
