Canine gastric cancer is a challenging diagnosis, with survival outcomes largely depending on the type of tumor, its stage, and the treatment plan. Surgery and chemotherapy are the two most commonly used treatment options for managing gastric cancer in dogs, particularly for malignant tumors such as gastric adenocarcinoma and leiomyosarcoma. This article explores the role of surgery and chemotherapy in improving the prognosis for dogs with gastric cancer, discussing how each treatment method contributes to survival rates and quality of life.

Surgery for Canine Gastric Cancer

Surgery is often the first line of treatment for dogs diagnosed with gastric cancer, especially when the tumor is localized and has not yet metastasized. The goal of surgery is to remove as much of the tumor as possible, offering the best chance for long-term survival and potentially curing benign tumors.

1. Tumor Removal
   Surgical resection is typically the most effective treatment for benign tumors like leiomyomas and some malignant tumors if caught early. The surgeon removes the tumor along with a margin of healthy tissue to ensure that no cancerous cells are left behind. In cases of malignant tumors, such as gastric adenocarcinoma, surgery can extend survival, but the prognosis remains guarded due to the high risk of metastasis and recurrence.
2. Gastric Outlet Obstruction Relief
   Many dogs with gastric tumors, particularly those located near the pyloric region, suffer from gastric outlet obstruction. Surgery can alleviate this condition, improving the dog’s ability to eat and digest food, which enhances their overall quality of life.
3. Prognosis with Surgery
   • Benign Tumors: For benign tumors like leiomyomas, surgery is curative in most cases, with dogs experiencing excellent long-term survival and minimal risk of recurrence.
   • Malignant Tumors: For malignant tumors like gastric adenocarcinoma, the prognosis is less favorable. Even with surgery, the median survival time is typically between 2 to 6 months, as metastasis and recurrence are common. Early detection and immediate surgical intervention are crucial in improving survival chances.

Chemotherapy for Canine Gastric Cancer

Chemotherapy is commonly used as a follow-up treatment after surgery or as the primary treatment in cases where the tumor is inoperable or has metastasized. Chemotherapy is more commonly used for cancers like lymphoma, which tend to respond better to this form of treatment.

1. Adjuvant Chemotherapy
   In some cases, chemotherapy is used after surgery to target any remaining cancer cells and reduce the risk of recurrence. Adjuvant chemotherapy can help slow the progression of the disease, particularly for aggressive tumors like gastric adenocarcinoma or leiomyosarcoma. However, its effectiveness varies, and not all dogs respond well to chemotherapy.
2. Palliative Chemotherapy
   For dogs with advanced-stage cancer or tumors that are too large or widespread for surgery, palliative chemotherapy is often recommended. While it may not cure the cancer, chemotherapy can shrink the tumor, alleviate symptoms, and improve the dog’s quality of life. Palliative chemotherapy can help manage symptoms such as vomiting, weight loss, and pain, giving the dog a better quality of life for its remaining time.
3. Prognosis with Chemotherapy
   • Lymphoma: Dogs with gastric lymphoma often respond well to chemotherapy, with some achieving remission. The survival rate for dogs treated with chemotherapy for lymphoma can be up to 12 months or more, depending on the stage of the cancer and the individual dog’s response to treatment.
   • Adenocarcinoma and Leiomyosarcoma: The prognosis for dogs with adenocarcinoma or leiomyosarcoma is more limited, as these tumors tend to be less responsive to chemotherapy. While chemotherapy can extend survival by a few months in some cases, the overall prognosis remains poor for these aggressive tumor types.

Combining Surgery and Chemotherapy

In some cases, a combination of surgery and chemotherapy provides the best chance of extending survival and improving a dog’s quality of life. Surgery is used to remove as much of the tumor as possible, followed by chemotherapy to target any remaining cancer cells and reduce the risk of recurrence. This multimodal approach is particularly useful in managing malignant gastric tumors, although the prognosis still depends heavily on factors like the tumor type, stage at diagnosis, and whether metastasis has occurred.

Factors Influencing Prognosis

Several factors impact the overall prognosis for dogs with gastric cancer, even when surgery and chemotherapy are used:

1. Tumor Type
   Benign tumors like leiomyomas have a much better prognosis than malignant tumors like gastric adenocarcinoma or leiomyosarcoma. The latter types are more aggressive and tend to metastasize early, reducing the effectiveness of treatment options.
2. Stage of Cancer
   The earlier the cancer is detected, the better the prognosis. Dogs diagnosed with localized tumors that have not yet metastasized have a higher chance of long-term survival, especially if surgery is performed promptly.
3. Response to Chemotherapy
   Some dogs respond better to chemotherapy than others. For example, lymphoma tends to be more responsive to chemotherapy, resulting in longer survival times, while gastric adenocarcinoma is less responsive.
4. Overall Health and Age
   A dog’s overall health and age play a significant role in determining the success of treatment. Older dogs or those with other health issues may not tolerate surgery or chemotherapy as well, which can limit treatment options and affect prognosis.

Surgery and chemotherapy are two key treatments used to manage canine gastric cancer, and their effectiveness depends largely on the type of tumor and the stage of the disease. Surgery is the best option for benign tumors and localized malignant tumors, while chemotherapy is often used as an adjunct or palliative treatment for more advanced cases. While these treatments can improve survival and quality of life, early detection remains critical to achieving the best possible outcome for dogs with gastric cancer.