Diagnostics
The vast majority of cancers, apart from hematologic malignancies, start as focal clones of cells and it is only once there is a sufficient tumor bulk that diagnosis becomes easier.
In order to enable an earlier diagnosis and increase the chances of a cure, there are an increasing number of screening programs targeted at identifying the asymptomatic or preinvasive stages of cancer. There has been great success in the use of routine screening programs for cervical and breast cancer. There is also the option of genetic screening, whereby those groups most at risk of developing cancer can be homed in on.
Tumors cause many symptoms that can aid in the diagnosis. Patients may have pain at the tumor site or a palatable mass. On the other hand, many patients seek medical advice on account of non-specific systemic symptoms such as weight loss, fatigue and anorexia. A general physical examination should include an assessment of the main symptomatic areas (e.g., site and size of mass), general signs (e.g., jaundice), functional capacity and precursor lesions.
After an initial consultation, the diagnosis of cancer may be suspected by both the patient and the doctor. However, advice about treatment can generally only be provided on the basis of a tissue diagnosis – either obtained by surgical biopsy or cytology. Following this, the extent and distribution of the tumor needs to be established. The staging systems vary according to the different types of tumors. For example, it may be staged according to its site or by the TNM (tumor, node, metastases) classification.