The dog cancer words, in plain English.

Adjuvant therapy

Treatment given after the main treatment, usually surgery, to lower the chance the cancer comes back. Chemotherapy after removing a tumour is a common example.

Benign

A growth that is not cancerous. It may still need removal if it causes problems, but it does not spread to other parts of the body.

Biopsy

Taking a piece of tissue so a pathologist can examine it under a microscope. A biopsy is what confirms whether a lump is cancer and, often, what type and grade it is.

Carcinoma

A cancer that starts in the cells lining organs and skin (for example the bladder or mammary glands). One of the broad families of cancer, alongside sarcomas.

Chemotherapy

Drugs that kill or slow rapidly dividing cells. In dogs the doses are generally gentler than in human medicine, and the goal is usually good quality of life, not cure at all costs.

CHOP

A common combination chemotherapy protocol for lymphoma, named for its drugs (cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone), given over several months.

Cytology (fine needle aspirate)

Using a thin needle to draw a few cells from a lump to look at under a microscope. Quick and low-stress, but it usually shows the cell type rather than the full grade, which needs a biopsy.

DLA (Dog Leukocyte Antigen)

The molecules a dog's immune system uses to display fragments of proteins so immune cells can inspect them. The canine equivalent of human HLA, and central to how a cancer vaccine is designed.

Grade

How aggressive a tumour looks under the microscope, based on features of its cells. Grade predicts behaviour. It is different from stage, which describes spread. Mast cell tumours, for example, are graded low or high on the Kiupel system.

Histopathology

The microscope examination of tissue by a pathologist. This is what delivers the definitive diagnosis, the tumour type, and usually the grade and whether margins were clean.

Immunohistochemistry

Special stains that reveal specific proteins in tissue. They help a pathologist confirm exactly what kind of cancer it is, especially when the cells are hard to identify.

Immunophenotype (B-cell / T-cell)

Which type of immune cell a lymphoma arose from. It matters: B-cell disease generally responds better and lasts longer than T-cell disease.

Immunotherapy

Treatment that works by directing the immune system against cancer, rather than attacking the cancer directly. Cancer vaccines and checkpoint-inhibitor drugs are forms of immunotherapy.

Malignant

Cancerous. A malignant tumour can invade nearby tissue and spread to other parts of the body, which is what makes it dangerous.

Margins (clean / dirty)

The rim of normal tissue removed around a tumour. "Clean" (or complete) margins mean no cancer cells were seen at the edge, suggesting it was fully removed. "Dirty" (or incomplete) margins mean cancer reached the edge, and more treatment may be needed.

Median survival

The midpoint of survival times in a study: half the dogs lived less, and half lived longer, sometimes by a lot. It is a description of a group, not a prediction for your dog. We explain why this matters in how to read a cancer study.

Metastasis

The spread of cancer from where it started to other parts of the body, most often the lymph nodes or lungs. "Micrometastasis" means spread too small to see on scans but already present.

Mitotic index (mitotic count)

A count of how many tumour cells are actively dividing, seen on the biopsy. A higher count usually signals a more aggressive tumour and is part of grading.

mRNA vaccine

A vaccine that delivers a genetic instruction (messenger RNA) telling the body to make a target protein, so the immune system learns to recognise it. The same technology behind recent human vaccines, now being applied to cancer. See how personalized cancer vaccines work.

Neoantigen

A protein fragment that appears only on cancer cells, created by the tumour's own mutations, and is found nowhere in healthy tissue. Neoantigens are the targets a personalized cancer vaccine is built to attack.

Palliative

Care aimed at comfort and quality of life rather than at curing or shrinking the cancer. Palliative radiation, for instance, can ease pain even when it will not cure the disease.

Prognosis

The likely course and outcome of the disease, based on what is known about similar cases. It is an informed estimate for a population, not a fixed sentence for an individual dog.

Radiation therapy

Focused high-energy beams used to kill or control cancer cells in one area. Often used when surgery cannot fully remove a tumour, or to relieve pain.

Remission

When signs of cancer shrink or disappear in response to treatment. "Complete remission" means no detectable disease; "partial" means it shrank meaningfully. Remission is not the same as cure, and cancer can return (relapse).

Sarcoma

A cancer that starts in connective or supporting tissues such as bone, muscle, fat, or blood vessels. Osteosarcoma (bone) and hemangiosarcoma (blood vessels) are examples.

Stage / staging

How far the cancer has spread in the body, usually numbered (for example Stage I to IV). Staging often involves bloodwork, imaging, and lymph node checks. Stage is frequently the single biggest driver of prognosis.

Standard of care

The treatment approach currently accepted as best-established for a given cancer, based on the available evidence. It is the benchmark that newer, experimental options are measured against.

Wide excision

Surgery that removes a tumour along with a margin of healthy tissue around and beneath it, aiming to leave no cancer cells behind. The standard surgical goal for many tumours.

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