Our Golden Oliver led the way when our site came online in 1997. And, his valiant struggle and loss to lymphoma helped us channel our efforts in more healthful and holistic ways. Yet, even with reduced vaccinations, filtered water, a chemically-clean environment, organic foods, and more, we did not escape a fibrosarcoma diagnosis with our Golden Darcy in 2005.
An Alarming Rate
One in three persons as well as companion animals are developing cancer, an alarming six million dogs annually diagnosed with a spontaneous, naturally occurring cancer. And, over 45% of dogs older than 10 years of age are dying of the disease, as cancer is the leading cause of death in this age group. Cases continue to increase, a recent study indicating that 63% of Goldens will die of cancer. It is believed that the next breakthrough will be in the form of targeted therapy, such as molecular targeted therapy or gene therapy.
Disease Trumps Species: Winning the War by 2015?
The National Cancer Institute Director issued a challenge to cancer researchers to “eliminate the suffering and death caused by cancer by 2015.” Our dogs may be critical to making that a reality. Humans and dogs have been partners for thousands of years, our canine friends quite active in the fight against cancer.
While researchers have a greater understanding of cancer biology, their artificially induced cancers in rodents have not afforded them with much success in human trials.
Yet, as Dr. David Waters, Co-director of the Purdue Comparative Oncology Program indicates, dogs and humans are the only two species that develop lethal prostate cancers. And, the breast cancer that affects dogs spreads to bones, just as it does in women. Further, osteosarcoma, which is the most frequent bone cancer of dogs, presents in the same way as it does for our teenagers. In fact, under a microscope, cancer cells from a teenager with osteosarcoma are indistinguishable from a Golden Retriever’s bone cancer cells.
According to researcher, Dr. Melissa Paoloni, this sharing of genetic signature has been the genomic proof of principle that the Comparative Oncology Program researchers have been seeking.
Comparative Oncology Findings
Researchers have discovered a genetic cancer link between dogs and humans. Jaime Modiano, V.M.D., Ph.D., University of Minnesota College of Veterinary Medicine and Cancer Center, and Matthew Breen, Ph.D., North Carolina State University’s Center for Comparative Medicine and Translational Research, collaborated on this research study. Their findings are published in the journal Chromosome Research, in a special March 2008 edition on comparative cytogenetics and genomics research.
Drs. Modiano and Breen have found that humans and dogs share the same genetic basis for certain types of cancer. Furthermore, the researchers say that because of the way the genomes have evolved, getting cancer may be inevitable for some humans and dogs.
“Many forms of human cancer are associated with specific alterations to the number or structure of chromosomes and the genes they contain,” Breen said. “We have developed reagents to show that the same applies to dog cancers, and that the specific genome reorganization which occurs in comparable human and canine cancers shares a common basis.” More specifically, Breen and Modiano found that the genetic changes that occur in dogs diagnosed with certain cancers of the blood and bone marrow, including chronic myelogenous leukemia (CML), Burkitt’s lymphoma (BL), and chronic lymphocytic leukemia (CLL), are virtually identical to genetic abnormalities in humans diagnosed with the same cancers.
“Interestingly, we found that the same translocation of chromosomes happens in dogs as in humans for the three blood and bone marrow cancers we studied,” Modiano said. Breen and Modiano conclude that despite millions of years of divergence, the evolving genomes of dogs and humans seem to have retained the mechanism associated with cancer, and that the conserved changes in the genomes have similar consequences in dogs and humans. The next step for Breen and Modiano is to use grants received from the National Cancer Institute to start pinpointing risk factors for cancer in various breeds of dogs.
Spontaneous Mammary Intraepithelial Lesions in Dogs—A Model of Breast Cancer was published November 2007 in Cancer Epidemiology Biomarkers & Prevention. Purdue University research reveals that pre-malignant mammary lesions in dogs and humans display many of the same characteristics, a discovery that could lead to better understanding of breast cancer progression and prevention for both people and companion animals. The similarity between canine and human lesions associated with breast cancer makes dogs an ideal model to study progression of the disease while it is still treatable.
The main form of treatment of breast cancer tumors has been surgical removal. Researchers, Mohammed and Miller, would like to find out if there is a way to identify the lesion early with noninvasive screening, such as ultrasound or magnetic resonance imaging. “Once a lesion is identified, it can be treated with hormonal therapy if it is estrogen receptor (ER)-positive, but for low-risk and ER-negative lesions, we can’t do anything but wait and watch to see if it grows into a tumor,” Mohammed said. “With a dog model, we could study these lesions and test different prevention modalities before it becomes a cancer.”
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