The Oncologist’s Perspective on Statistics: Part One

I know what you are thinking. Statistics … ick, boring. I agree. I was never a fan of learning about stats. In fact, statistics was one of my least favorite classes in undergrad.

But when you are dealing with the overwhelming diagnosis of cancer, there are a ton of statistics to learn. How long will my dog live without treatment? With treatment? What is the response rate to a protocol? What is the difference between median and mean survival times? What about disease free interval? Is your head spinning yet?!

I was also required to learn many stats during my residency and for my oncology boards.  By this time, I actually liked learning the stats … because while cancer can be unpredictable, statistics are practical. Statistics help me predict many things about cancer for my patients.

For example, osteosarcoma is the most common bone tumor. In fact, 85% of dogs with cancer in the bone will be diagnosed with osteosarcoma. Statistics tell us that three-quarters of these tumors develop in the limbs, with the front legs twice as likely develop this tumor.  The most common locations are towards the knee and away from the elbow – the top of the shoulder, the wrist, and the knee (bottom of femur or top of tibia). Osteosarcoma is typically seen in large and giant breeds including  Great Danes, St Bernards, Irish Setters, Rottweilers, German Shepherds, Golden Retrievers, and Doberman Pinschers.

So when last month, I met George, a middle aged St. Bernard with a lytic lesion in his radius bone at the wrist, I could predict to his Guardians with high likelihood that George’s diagnosis was osteosarcoma.

With many clinical studies and statistical analyses, we can predict that dogs treated with amputation alone have a median survival time of four to five months, with 90-100% dying at one year and only 2% are still alive after two years.  With statistics, we can predict that the median survival times for dogs treated with amputation and chemotherapy increase to 10 to 12 months, with 20-25% of dogs still alive after 2 years. That’s a good amount of information, thanks to statistics.

So, as you can see, statistics are helpful and something you will undoubtedly want to learn, because they give you expectations and will help you formulate your treatment plan.

In my next blog, I will discuss some of the limitations is statistics and see why they are not always helpful. For more information on osteosarcoma or cancer-related statistics, check out the Dog Cancer Survival Guide.