Sick American dogs get first shot at cancer drugs

Dogs with cancer in the US are now entitled to receive experimental drugs – before the drugs are available for humans. Twelve trials are under way on groups of 15 to 60 dogs, and in several of them cancers have disappeared.

"We've had dramatic remissions in dogs with really aggressive cancers," says Chand Khanna, head of the Comparative Oncology Trials Consortium newly formed in Bethesda, Maryland, by the US National Cancer Institute. "We've also had responses allowing dogs to have their original cancers surgically removed," he says.
Forget mice and rats

The rationale is that unlike mice and rats, which are kept in a highly regimented experimental setting, pet dogs experience cancer in a similar way to humans. As in people, cancers in dogs spread to form secondaries and can become resistant to drugs, and the animals can have relapses.

Not only that, but dogs suffer from cancers as variable as those affecting humans, so treating them gives us a much better idea of what would happen in a cross-section of humans than we could gain from lab studies of mice.

The consortium consists of 19 veterinary schools, and there are plans to extend it to Europe. Owners can opt for conventional drugs or experimental ones, including some that are untested in humans and others that are already undergoing trials, but that need additional animal data – for example on dosing – before they can proceed to the next stage.

As well as looking after their sick dog, owners can help gather data for the researchers. "They're given notebooks so that they can complete assessments of quality of life, appetite, demeanour and perhaps even collect some specimens," says Khanna.
Sensitive area

Because owners carry on caring for the dogs, and because the hope is that pet dogs will get better as a result of the treatment, the approach also challenges claims by antivivisectionists that all experimentation on animals is wrong. "I understand their sensitivities, and we've had informed discussions with individuals, and some do see the value of helping dogs with cancer in this way," says Khanna.

"This raises serious concerns with respect to what the dogs may have to endure," says Nedim Buyukmihci, a vet consultant to the British Union for the Abolition of Vivisection.
Every dog matters

Khanna says, however, that the top priority for every dog is their well-being. "It's important that the trials are designed with the care of the animals as priority, and also that there's an informed consent process each time," he says.

Cancer researchers in Europe are watching closely to see whether to join the consortium. "Studying dogs, with their owners' consent and following ethical guidelines, after they have naturally developed cancer, is an interesting approach to learning more about the disease," says Joanna Owens, communications manager at the Cancer Research UK charity in London. "We look forward to following the progress of this initiative and the findings that come out of their research."

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Cancer

Defining cancer

Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues. Cancer cells can spread to other parts of the body through the blood and lymph systems.

Cancer is not just one disease but many diseases. There are more than 100 different types of cancer. Most cancers are named for the organ or type of cell in which they start -- for example, cancer that begins in the colon is called colon cancer; cancer that begins in basal cells of the skin is called basal cell carcinoma.

Cancer types can be grouped into broader categories. The main categories of cancer include:

* Carcinoma - cancer that begins in the skin or in tissues that line or cover internal organs.


* Sarcoma - cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.


* Leukemia - cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood.


* Lymphoma and myeloma - cancers that begin in the cells of the immune system.


* Central nervous system cancers - cancers that begin in the tissues of the brain and spinal cord.

Origins of cancer

All cancers begin in cells, the body's basic unit of life. To understand cancer, it's helpful to know what happens when normal cells become cancer cells.

The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old or damaged, they die and are replaced with new cells.

However, sometimes this orderly process goes wrong. The genetic material (DNA) of a cell can become damaged or changed, producing mutations that affect normal cell growth and division. When this happens, cells do not die when they should and new cells form when the body does not need them. The extra cells may form a mass of tissue called a tumor.


Not all tumors are cancerous; tumors can be benign or malignant.

* Benign tumors aren't cancerous. They can often be removed, and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body.


* Malignant tumors are cancerous. Cells in these tumors can invade nearby tissues and spread to other parts of the body. The spread of cancer from one part of the body to another is called metastasis.

Some cancers do not form tumors. For example, leukemia is a cancer of the bone marrow and blood.