Basic cancer biology
To begin to understand Cancer of Unknown Primary (CUP) one needs to understand first that:
- The human body is composed of billions of cells. These cells are genetically programmed to do various things throughout our lifetime. We need new cells to replace worn out cells that die in a regular cycle.
- If (the DNA in) a cell becomes faulty it can start growing uncontrollably and form a tumour (literally 'swelling' but in the Cancer context the word is used to denote abnormal growth of tissue).
- If the tumour is abnormal it is known as "malignant"; if it is not cancerous it is known as "benign". (The word 'lesion' is sometimes used. Lesions are caused by any process that damages tissues. A cancerous tumour is an example of a lesion.)
- A benign tumour does not spread within the body but an untreated, malignant tumour is likely to metastasise or spread (see cancer spread).
- Early diagnosis is important. However, a tumour may not be apparent and the symptoms may not be recognised by the patient or doctor.
Cancer with an unknown starting point is referred to in many different ways but, increasingly, as Cancer of Unknown Primary (CUP). Other terms include: Tumour of Unknown Origin, Metastatic Malignancy of Unknown Origin, Occult Primary Malignancy (Occult meaning hidden from the Latin Occultus) and, more specifically, Carcinoma of Unknown Primary.
CUP - a summary definition
CUP - where the origin of the cancer cannot be determined in assessment before treatment and sometimes remains hidden - probably accounts for about 5% of cancer diagnoses; but this figure depends on how CUP is defined. Most CUP definitions are of metastatic carcinoma of unknown primary where the primary is not detectable.
- Clinical presentations are usually non specific and often involve metastasis in more than one organ.
- Usually, the most important step in diagnosis is the biopsy because this allows a general cancer categorisation of carcinoma, sarcoma, lymphoma or melanoma. Our focus is on carcinoma where further definitions are needed to achieve effective treatment.
- Some further classifications are usually possible from the biopsy sample which will help determine likely treatment. But in the case of CUP, the cells have lost their unique features in the cancer spread. This makes identifying the original cancer cells (the target of systemic treatment e.g. by chemotherapy) difficult.
- Because carcinoma of unknown primary may originate in any epithelial cells in the body, and CUP biology is not understood (other than that the primary stays small or disappears yet spreads - metastasises - unpredictably) it is a challenging diagnosis for the cancer doctor as well as the patient.
- There are few standard treatments, because the cancer is likely to be different for every patient, with widely different outcomes.
- Improving genetic, pathological and radiological techniques will reduce the incidence of CUP in the future.
There are a number of useful explanations of CUP and its treatment to be found on the web. There is an encouraging and informative article here. A fuller explanation of CUP, as understood by Jo's friends, is captured in articles published in journals to be found in our archive.
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Cancer of Unknown Primary (CUP) is metastatic cancer with no radiographically or pathologically detectable primary tumour after an ‘adequate’ diagnostic evaluation.
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Ron on the 130 km Etape Caledonia. With son Jimmy they raise £2,000 for Jo's friends through JustGiving
