At OncoCare Cancer Centre, we sometimes see patients who have received a report and are confused by the cancer names or terminology. Some patients have been informed by their treating doctor or surgeon that they have a lump removed and that it is a tumor (or tumour). They next receive a report that may be difficult to understand. What is the difference between the different terminologies?

1. Is this a malignancy?

This is probably the most basic question that a patient should ask. Not all lumps are malignant or cancerous. Fibroadenoma of the breast, fibrocystic disease of the breast are some examples of benign conditions. A benign tumour in general does not invade or spread, and frequently removal by surgery is the cure. A formal definition of cancer characteristics are: a tumour that has its own growth signals, that resists signals that informs it to stop growing (like a middle-age belly!), resist cell death, multiplies forever and is able to stimulate its own blood supply (angiogenesis).

Like many things in biology, there are some tumours that somehow do not fulfil the entire criterion. A proper discussion may be necessary, sometimes with the help of a pathologist.

Carcinoma, Sarcoma, Myeloma, Lymphoma, or Leukemia

2. Where does the tumour arise from?

Carcinoma (from the Greek word describing a “crab”) is the term for cancers that arise from epithelial cells. These include the common cancer sites that we know such as breast, colon, stomach, skin and lung cancer. Epithelial cells are the cells lining the external or inner surfaces of our body and organs. Remember that the cancer does not declare under microscopic examination its organ of origin such as the lung, stomach, breast, ovary or colon. In fact, the carcinoma may be described because it has features of “skin type” (squamous cell), or gland-forming (adenocarcinoma) features. There can also be complete disorganisation with unrecognisable features (anaplastic). In addition, sometimes the cancer is described based on its cell size, such as large or small cell carcinoma. There can certainly be mixed cell types seen in a biopsy (adenosquamous).

Other elements of our body can give rise to cancers of the muscle, bone, cartilage and connective tissues known as sarcoma.

The blood and lymph system is where lymphoma, myeloma and leukaemia (or leukemia) get their origins. Here is where the naming gets a bit complex. Most people might have heard of Hodgkin and non-Hodgkin's lymphoma but there are actually many types of lymphoid tissues within our system that can turn malignant. Although most people might know what breast carcinoma is, they might not be familiar with NK/T cell lymphomas (or try Mycosis Fungoides and Sezary Syndrome!). Under the World Health Organization (WHO) classification of lymphomas, there are more than 60 types.

TABLE: WHO Classification of mature B-cell, T-cell, and NK-cell neoplasms (2008)

*Provisional entities for which the WHO Working Group thought there was insufficient evidence to recognize as distinct diseases at this time.
^These lesions are classified according to the leukemia or lymphoma to which they correspond. Diseases shown in italics were newly included in the 2008 WHO classification.

Myeloma is a type of malignant B cell neoplasm arising from plasma cells. Other specialized tissues in our body can turn malignant and they do have unusual (non-conventional) names such as glioma (from brain and central nervous system tissues), melanoma (from nevus or moles) and germinoma (germ cell tissue such as testes or ovaries).

3. Is this a primary or metastatic tumour?

A primary tumour or cancer arises from where its tissue of origin is found but a secondary or metastatic tumour comes from dissemination from another site. The tumour seen in the lung may arise from the lung (primary lung cancer) or from elsewhere (metastasis). Even if the pathology reports the cancer cell type, (say adenocarcinoma cells from a biopsy of a lung lesion), it can be a primary or metastasis. There are some special tests that can be performed on the tumour to differentiate where it originated. Immunohistochemistry is a technique to stain tumour cells on a slide with antibodies carrying a stain. For example, breast cancer cells might have oestrogen (or estrogen) receptors (ER) and staining positive for this hormone receptor may give a clue that the adenocarcinoma started from breast tissues.

Identifying the cancer (whether it is carcinoma, sarcoma, myeloma, lymphoma or leukaemia) is just the beginning but it is important in many situations using advanced, histopathological and molecular techniques as it can affect treatment and prognosis.

“Expert knowledge means better care for cancer”

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