Performance status (PS) The scales and criteria used to assess how the cancer affects the daily living abilities of patients and to determine appropriateness of treatment. The WHO/Eastern Cooperative Oncology Group (ECOG) PS used in this book is as follows:
0: fully active, no restrictions on activities
1: unable to do strenuous activities, but able to carry out light housework and sedentary activities
2: able to walk and manage self-care, but unable to work; out of bed for more than 50% of waking hours
3: confined to bed or a chair for more than 50% of waking hours; capable of limited self-care
4: completely disabled; totally confined to a bed or chair; unable to do any self-care
5: dead.
Staging Staging is done to assess the extent of disease, choose the appropriate treatment, and assess the likely outcome of the disease. TNM staging denotes tumour, node, and metastatic status. Composite staging involves grouping various T, N, and M combinations into four stages (I–IV). The following prefixes are added to staging to indicate the method of staging:
c: clinical staging based on physical examination, imaging and endoscopy
p: pathological staging after surgery
y: denotes staging after neoadjuvant therapy.
Neoadjuvant therapy Therapy is given before a definitive treatment such as surgery to facilitate the procedure and/or improve the chances of cure.
Adjuvant therapy Therapy is given after a definitive treatment such as surgery or radiotherapy with the aim of destroying micrometastatic residual disease and thereby increasing the chances of cure.
RECIST criteria (Response Evaluation Criteria in Solid Tumours) Criteria used to assess treatment effectiveness. Most often the assessment is made radiologically. Based on these criteria, treatment responses are categorized as complete response, partial response, stable disease, or progressive disease.
Gross tumour volume (GTV) The gross demonstrable extent and location of the tumour. The GTV is delineated using clinical (e.g. physical examination), anatomical (e.g. CT, MRI), and/or functional-imaging modalities (e.g. PET, functional MRI). In case of post-operative radiotherapy after complete macroscopic resection, there is no GTV to define and only a CTV needs to be delineated.
Clinical target volume (CTV) The volume of tissue that contains a demonstrable GTV and/or subclinical malignant disease with a certain probability of occurrence considered relevant for therapy. The definition of the CTV is derived from the extent of microscopic spread based on histological examination of post mortem or surgical specimens, biological characteristics of the tumour, local recurrence patterns, and the experience of the radiation oncologists.
Planning target volume (PTV) A geometrical concept introduced to ensure that the prescribed radiation dose will actually be delivered to all parts of the CTV with a clinically acceptable probability, despite geometrical uncertainties such as organ motion and setup variations. The PTV is derived by adding a margin to the CTV which takes into account the physiological organ motions and variations in patient positioning setup and alignment of the therapeutic beams during the treatment planning, and through all treatment sessions.
Atypical resection of liver A method of resection where the tumour is peeled out of liver parenchyma using a modern ultrasound knife. This allows the parenchyma to be crushed while leaving the bile ducts and vessels intact. Using this technique complete tumour removal can be performed regardless of the surgical resectability as defined by the anatomical borders of the liver segments.