biopsies and investigational studies

There are various cancers where fine needle aspirates have become the customary diagnostic procedure. A case in point is canine lymphoma. In approximately 9 of every 10 cases, the disease involves accessible lymph nodes that can be sampled with a small needle, the malignant cells readily dislodge from the node with slight negative pressure, and the diagnosis is usually straightforward. Some staging methods, which identify how far the disease has advanced, also do not require a precise histological classification. The presence of malignant cells, along with physical exam findings, blood tests, imaging, and analysis of a bone marrow sample are sufficient to stage the disease. Management options include various measures that range from palliative care to keep the patient comfortable for a few days to weeks, to more aggressive chemotherapy that may lead to extended remissions.

This tried-and-true approach has served the profession and its patients well for over 30 years, but recent work recognizes that staging canine lymphoma using additional criteria has value to determine the best management protocols. A biopsy allows the pathologist not only to appreciate the appearance, shape, and size of the cells (morphology), but also to gain insight into the disturbances of the architecture in the same tissue. The astute pathologist can infer if cells are expanding from a center or contracting toward a center, the proportion of normal remaining tissue within and around the tumor, the number of cells in the active process of division, and other important features. Based on this, we now recognize “lymphoma” as a group of more than a dozen different tumors, each originating from a different type of lymphocyte with different morphological and architectural features. These can have different behaviors and response to treatment, so their proper classification can be useful to evaluate progression and to guide the management of the disease in otherwise healthy dogs. Nevertheless, the cost and risk of a biopsy cannot always be justified. For example, in cases where circumstances preclude consideration of multiple treatment options, it may be less important to identify the specific type of lymphoma. These circumstances may include the presence of another severe, life-threatening disease, conditions that may limit the use of chemotherapy, and even financial considerations where available funds would be better spent on treatment, rather than on diagnostic tests.

Sometimes, the family of a cancer patient may be asked to consider participation in a clinical or investigational trial. Clinical trials are meant to test new drugs or compounds to treat a specific condition. Investigational trials are used to study the cause or behavior of a disease, and they may or may not involve treatment. Because trials are experimental by nature, benefits are usually attained by (and meant for) future generations of patients, although participants can sometimes receive tests and/or treatment at no or reduced costs. A biopsy is almost always required for participation in such trials. Therefore, whether a study is available or not, it is important for people to discuss the potential benefits, risks, and costs of a biopsy in the diagnosis of cancer. Attending veterinarians must consider the willingness of their pathology service lab to provide prompt, detailed information, as well as how this information will influence treatment decisions. The veterinarian and the family also should carefully consider if there are benefits of participation in available trials. Only in this way can we advance the standard of practice and the standard of care for cancer patients now and in the future.

We routinely request that study participants that are affected with one of the cancer types we study consider providing biopsy samples. Whenever possible, we make arrangements with the attending veterinarian to obtain the biopsy using our specifications, including placing the tissue in transport media we provide. Generally, these arrangements require at least 24 hr advance notice. For details, please see the forms that provide general information about the studies and specific information for veterinarians in this section.

This document was prepared in collaboration with the Briard Medical Trust

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