Dedicated to Ana Maldonado
1. Just as in women, the most common female malignancy in dogs is breast cancer.
2. Just as in humans, 1% of male dogs develop breast cancer too.
3. The incidence of breast tumors in dogs is three times higher than it is in women.
4. Just as in women, female sex hormones play a causal role in breast cancer.
5. Just as in women, obesity and a high fat diet are risk factors for breast cancer.
6. Just as in women, the most common sites of metastases are the regional lymph nodes and the lungs.
7. Unlike in women, the average survival for dogs with metastatic Stage III and Stage IV breast cancer is 3-7 months.
8. Just as in women, dogs develop inflammatory breast cancer.
9. Just as in women, dogs with estrogen-positive breast cancers have a better prognosis.
10. Just as in women, there is no difference in survival between radical surgery and more conservative surgery such as lumpectomy.
11. For most breast cancers, chemotherapy has not been fully evaluated, while other therapies such as hormonal, targeted, or radiation treatment have not been studied or are not beneficial.
12. In a study published in 2006 that evaluated 1320 women, those with breast cancer were twice as likely to have owned dogs when compared to healthy women. A statistical analysis of this finding showed that the probability that this observation was due entirely to chance was 0.0000003. (Medical Hypotheses, 2006, 67, 21-26) The authors of this study, which was conducted at the University of Munich, concluded that “risk factors from dogs could contribute to the carcinogenesis of human breast cancer.”