Mast cell tumors (MCT) are one of the most common skin tumors in dogs and can vary in how quickly they grow. The speed of growth and how far along the tumor is will be important considerations for your veterinarian when it comes to developing a treatment plan. It is important to understand how quickly these tumors can grow so you can stay ahead of their progression. In this blog post, we will discuss the growth rate of mast cells tumors in dogs, signs to look for, and the steps you should take if you believe your pup is at risk. We hope that this post gives you the information you need to feel confident in your pet’s health and provide the best care possible.
How does this cancer typically progress?
This tumors behavior is complex and depends on many factors. Typically, the pathologist can determine how aggressive the cancer is based on several factors when the tumor cells are examined under a microscope. The tumor is rated on a scale of I to III, with I being significantly less aggressive than III MCTs. A higher propensity for metastasizing (spreading to other parts of the body) is present in higher grade tumors.
Typically, the prognosis is less favorable if:
What is a mast cell?
Many body tissues contain a type of white blood cell called a mast cell. As allergy cells, mast cells contribute to the allergic reaction. Mast cells release chemicals and substances when exposed to allergens (substances that cause allergies), a process known as degranulation. One of these compounds is histamine. The most well-known effects of histamine are itchiness, sneezing, and runny nose and eyes, which are typical signs of allergies. However, when histamine (and the other compounds) are released in large quantities (with mass degranulation), they can have full-body effects, including the potentially fatal allergic reaction anaphylaxis. ( via Wikimedia Commons / Joel Mills (CC BY-SA 3. 0. ).
Recent, rapid tumor growth and fixed, ulcerated tumors are two things that can be discovered from a history and physical exam that are generally accepted to carry a more guarded prognosis in dogs with MCTs. 6-8 Although there are few publications on these characteristics, an early study found that dogs with slow-growing tumors had a survival rate that was twice as high at 30 weeks after MCT excision compared to dogs with more rapidly growing masses. 8 In biological terms, the capacity for rapid growth and the capacity to bind to deeper tissues are outward signs of more aggressive behavior. The physical location of a tumor can also influence its biological behavior; this subject is more debatable, and the relevant regions and published papers are highlighted as follows:
One of the most widely used predictors of canine MCT behavior is a histologic grading system (I-III) that was created for classification of MCTs affecting haired skin. However, histologic evaluation is subject to operator subjectivity, leading to extremely disparate pathologists’ grades for the same tumor. In a study with ten pathologists grading the same 60 MCTs, only four tumors received the same grade from all pathologists, and six of the MCTs received all three grades. The discrepancy was thought to be caused by variations in the references used to grade the MCTs, with six different references being used. 28 The Patnaik grading system was employed by all pathologists in a subsequent study that utilized the same tumors and pathologists. Only 16 of 60 tumors received the same grade from all participants, and only three of 60 tumors still received all three grades, despite an improvement in mean agreement. 27 The reliance on an MCT’s grade to predict its behavior is seriously questioned by the subjectivity and variation among pathologists. Additionally, the majority of MCTs are grade II, and surgery is typically required to treat them. There is ongoing discussion and research regarding how to recognize the subset of grade II tumors that will exhibit this aggressive behavior.
Mast cell tumors (MCTs) arise from malignantly transformed mast cells. The majority of these tumors develop in dogs as primary skin tumors. They account for about 20% of all reported skin tumors in dogs, making them the most prevalent type. Any breed may develop MCTs, but some breeds, such as golden retrievers, Labrador retrievers, Boston terriers, boxers, and pugs, are predisposed to the condition. Pugs are more likely to have multiple MCTs when they are first diagnosed (56% of pugs in one study had MCTs), but these tumors have more benign behavior and rarely cause death. Dogs of any age can be impacted by MCTs, but typically middle-aged to older dogs are most affected. An underlying etiology for most tumors cannot be identified. Breed predilections support some component of underlying genetic causes. 25%–30% of intermediate to high-grade tumors contain mutations in the c-kit tyrosine kinase receptor, which can cause the malignant transformation of mast cells. The prognosis and treatment options for MCTs will be further discussed in relation to 3,4 KIT mutations.
Although this is generally not supported, there are still concerns about MCTs in the inguinal areas, especially involving the prepuce or scrotum. Historically, the “back half” of the dog was thought to have a worse prognosis. In one study, dogs with MCT in the perineal and/or inguinal regions were given intensive treatment; the majority of these dogs received trimodality therapy, which consists of surgery, radiation, and chemotherapy. The MST was 37 months, and the authors came to the conclusion that therapy dogs with perineal or inguinal MCTs can function well with the right training. Importantly, these dogs underwent a more aggressive course of treatment than the majority of dogs with MCTs at other cutaneous sites. In a subsequent study, dogs with inguinal or perineal MCTs were treated with a variety of therapies, and the results were compared to those of dogs with MCTs in other cutaneous locations. Separating the 12 dogs with preputial or scrotal MCTs from the other inguinal or perineal tumors resulted in a noticeably shorter disease-free interval (4). 2 months) compared to the 84 dogs with tumors in noninguinal cutaneous sites (33). 9 months). The results may have been skewed because 23 dogs with preputial or scrotal MCTs were significantly more likely to have received chemotherapy. The study’s power may not have been sufficient, according to the authors, to distinguish between the locations. Further research is required because scrotal and preputial MCTs may exhibit a more malignant biological behavior.
Mast cell tumors (MCTs) are the most prevalent malignant skin cancer in dogs, and there is a significant amount of variation in their biological behavior, according to Laura D. Garrett Department of Veterinary Clinical Medicine, University of Illinois College of Veterinary Medicine, Urbana, IL, USA. The majority of MCTs are curable with the right local therapy, but a small percentage exhibit malignant behavior that could spread to the lymph nodes, liver, spleen, and other organs and become a systemic cancer. It is challenging to forecast the behavior of any particular tumor due to its variable behavior. Thus, there is uncertainty when determining a specific dog’s prognosis, whether staging tests to check for metastasis are required, and even what treatments will be required for the best outcome due to the variability. There are disagreements over the best course of treatment for achieving local control of these tumors as well as the likelihood of the development of diffuse metastasis or systemic disease. In addition to summarizing the literature on the contentious issues surrounding the more severe form of this disease, this article will briefly discuss the diagnosis of MCTs in dogs and offer suggestions based on published studies. Keywords: mitotic index, mastocytosis, tyrosine kinase inhibitor, histologic grade.
FAQ
What is the life expectancy of a dog with a mast cell tumor?
These tumors all have a poor prognosis, with median survival times of under 4 months. They behave aggressively and require more aggressive therapy. The median survival time of these tumors was more than 2 years overall, but some of them exhibited aggressive behavior in spite of their low grade.
Do mast cell tumors spread quickly in dogs?
Some may be around for months without doing much growing, while others may appear out of nowhere and grow quickly. Sometimes, after months of no change, they can grow quickly. They might seem to change in size, growing or shrinking even on a daily basis.
What are the stages of mast cell tumors in dogs?
Dog mast cell tumor stages Stage I – Single tumor with no metastases Stage II: A single tumor that has spread to the nearby lymph nodes, which is causing secondary growth. Stage III refers to numerous skin tumors or a sizable tumor that has spread to the subcutaneous tissues.
Can mast cell tumors grow in a week?
A mast cell tumor (MCT) is a specific kind of tumor that develops as a result of the tissue’s mast cells rapidly replicating and dividing. Mast cell tumors may develop gradually over time or suddenly and dramatically.