The term cancer is generally used for malignant neoplasms. A malignant tumour displays invasive growth, i.e. growth beyond its anatomical boundaries, and can result in the formation of distant metastases. Cancer arises from unregulated cell growth, due to alterations in the genome of cells. The cells consequently no longer react to regulatory signals. The accumulation of various genetic defects in a cell ultimately lead to cancer. Cancer is often preceded by a histologically recognizable premalignant stage, called dysplasia. During the past decades, considerable advances have been achieved in characterizing the genetic changes in cells which lead to the beginning of the cell growth. The most important genes involved in these processes are oncogenes, tumour suppressor genes and the so-called DNA mismatch repair genes.

Squamous cell carcinoma is the most common variety of malignant oral tumour. Most commonly oral carcinomas occur at the lateral tongue surfaces and at the anterior part of the floor of the mouth. If oral cancer is suspected, a dentist will refer the patient to an oral and maxillofacial surgeon who will perform a biopsy. When the diagnosis squamous cell carcinoma is established, the patient will be referred to a multidisciplinary head and neck oncological centre for additional diagnostics and treatment. Depending upon size, location and extent of the tumour and the presence or absence of regional metastases, the management may include surgical excision, radiotherapy or a combination of surgery and radiotherapy. The prognosis is mainly determined by the size of the tumour and regional lymph node involvement. Therefore, early detection is of utmost importance.

The medical treatment of solid tumours depends on many different factors. The choice of drug is stipulated by the tumour type, the stage of the disease and a number of patient characteristics, such as biological age, co-morbidity, and general performance status. The treatment can be curative, palliative or (neo-)adjuvant in nature. The groups of drugs which are used are hormones, cytostatics, immune-modulating drugs and (a new group) targeted-drugs consisting of small-molecules and monoclonal antibodies. Only a few tumour types are curable with chemotherapy in an advanced stage. In some tumour types an increase in life-expectancy can be achieved; other tumours are hardly or not at all sensitive to medical treatment. Treatment is limited by the side-effects of the drugs. With supporting medication some of the side-effects can be alleviated. With palliative therapy the aim is to improve the general condition by temporarily inhibiting the tumour with minimal side effects. Adjuvant chemotherapy raises the chance of cure after primary treatment with surgery or radiotherapy.

Soft and hard tissue defects in the head and neck region after benign or malignant tumour resection, can be reconstructed by surgical techniques, such as tissue transplantation, and/or prostheses. The aim of reconstruction is to restore the original esthetics and functions of the bone and soft tissues that have been resected. The introduction of free vascularized osteomyocutaneous fibula and iliac crest flaps improved the surgical possibilities of reconstructing the mandible and the maxilla. With respect to oral rehabilitation, a reconstruction of the mandible and the maxilla should be carried out in such a way that it provides an adequate base for inserting endosseous implants, which will retain a removable or fixed prosthesis. This requires good interdisciplinary planning, in which the plan for prosthetic treatment determines, in part, the choice of reconstruction method.