Canine Health Foundation Grant #01384-A
Urinary bladder cancer (transitional cell carcinoma, TCC) strikes 20,000 to 30,000 pet dogs each year in the United States, and TCC prevalence is increasing. Breeds with the highest risk for developing this type of cancer include the Scottish Terrier, West Highland White Terrier, Shetland Sheepdog, Beagle and the Wire Hair Fox Terrier. Although substantial progress is being made in TCC treatment, most dogs eventually die from the cancer. The purpose of the proposed work is to determine a new method to measure TCC masses in the bladder, and therefore to be able to accurately determine the response to TCC therapy. There are three main reasons that this is so important. 1. In each individual dog, the change in tumor size is used to determine if the treatment the dog is currently receiving is being effective in that dog. If the cancer is regressing or remaining stable, the same treatment is continued. If the cancer is increasing in size, it is important to recognize this and switch to a different treatment. 2. There are several new therapies that may potentially work against TCC, and it is crucial to be able to measure the tumor size and thus the efficacy of these new therapies in dogs in clinical trials. 3. The currently available methods to measure TCC all have disadvantages or serious limitations. Computed tomography (CT, CAT scan) is the most accurate way to measure tumor volume, but this test is prohibitively expensive for most pet owners. CT also requires general anesthesia, and visualization of bladder masses requires urinary catheterization, both of which involve some risks. Two dimensional ultrasound (2D US) is currently most often used to measure TCC at our institution and other institutions. Tumor volume is estimated by evaluating US images that are made from two different angles, as the US probe is moved over the bladder multiple times. This technique may be inaccurate if the bladder is not distended to the same degree each time the ultrasound exam is done on the dog, or if the US probe angle varies. To increase the accuracy, at our institution, the same person performs the US on each dog at each of the dog's visits. This is not a practical approach for many hospitals. Here we propose the evaluation of an exciting novel approach to measure TCC masses: three dimensional ultrasound (3D US). New, cutting edge technology allows 3D images to be produced from a single scan with a 3D US probe. In fact, once the US probe is placed in an optimal position over the bladder, the operator does not move the probe. Instead, an automated process captures the 3D volume with no operator movement. Thus the results are much less dependent on the same person doing each scan. In addition, the images are produced with the dog awake, and bladder catheterization is not expected to be required. In the study, 3D US will be tested in 10 dogs with comparison made to the gold standard, CT. The success of this study will allow an accurate, repeatable and cost-effective method for monitoring therapeutic success and allow for more timely and accurate adjustments in therapeutic regimens. Although the cost of 3D US equipment has been initially high, like most new technologies, the costs are rapidly dropping to an affordable investment in veterinary hospitals. In addition to imaging TCC, gaining experience with this technique is expected to allow its use to be expanded into assessing other types of cancer.