A disease that cats are prone to: mammary gland cancer ... If you find a lump in your chest, go to the hospital immediately [Rianimaru]

What disease?

In this day and age, it is said that one-third of the cats who die from diseases do not die from malignant tumors or "cancers." Breast cancer is the most common of these. As in humans, 99% of cases occur in females, but males can also be affected in rare cases.

The risk is greatest for older neutered female cats aged 10-12 years. It is said that more than 80% of mammary gland tumors in cats are malignant mammary adenocarcinoma. If you find a lump on your cat's chest, take him to the veterinarian immediately.

What if I get caught?

If mammary adenocarcinoma is suspected at the hospital, the size of the tumor is measured and the regional lymph nodes that are prone to metastasis, such as the inguinal and axillary lymph nodes, are palpated for swelling. The first test required for diagnosis is a cytological examination of the tumor itself. Mammary gland cancer in cats cannot be definitively diagnosed by cytological examination, so a definitive diagnosis can be made by pathological examination of the surgically excised tumor. Therefore, it is an essential examination for differential diagnosis.

At the same time, in order to understand the stage of cancer, an ultrasound examination of the regional lymph nodes is performed to check for swelling. A chest X-ray is also essential because the lungs are prone to distant metastasis. If you wish to undergo surgery as other tests, blood tests, urine tests, and abdominal and heart echo tests will be performed as needed to grasp the general condition.

There are four stages of mammary adenocarcinoma, and the prognosis and treatment methods vary depending on which stage. Stage 1 is tumor diameter less than 2 cm without lymph node metastasis. Stage 2 has no lymph node metastasis and tumor diameter is 2-3 cm. Stage 3 has lymph node metastasis, or tumor diameter ≥3 cm with or without lymph node metastasis. Stage 4 is the case of distant metastasis to the lungs.

Prognosis is determined by comprehensive evaluation of tumor size, presence or absence of metastasis, and postoperative pathological grade, but metastasis and large tumors larger than 3 cm are poor prognostic factors. Stage 4 is not indicated for surgery, so it is treated with palliative care such as setting up an oxygen chamber at home and taking painkillers, but in many cases it dies within about a month. Stage 2.3 cases are candidates for unilateral mastectomy. Surgical treatment is recommended because there is data that the 50% survival time is about 421 days with surgery and 100 days without surgery.

Mammary adenocarcinoma can occur multiple times, and if there is a tumor on the other side of the breast, one month later, one side is completely removed without surgery at once. The reason why surgery cannot be performed at once is that the surgery involves a fairly wide area, so the inflammatory reaction is quite strong, and the overproduction of immune cells called a cytokine storm can occur, which can lead to shock.

Surgery itself is performed under hospitalization management, and it is often hospitalized for about a week. Regardless of the presence or absence of lymph node metastasis, the regional lymph nodes are also removed, so the lymph that originally flowed into the lymph nodes has no place to go, and the lymph and inflammatory serous fluid accumulate, so a drainage tube called a drain is inserted. Sometimes. In that case, if the amount of serous fluid is reduced enough to remove the drain, the patient will be discharged from the hospital.

In addition, as postoperative chemotherapy, doxorubicin, an anticancer drug that cuts the DNA of cancer cells and kills cancer cells, is injected intravenously over 30 minutes every 3 weeks 3-4. 50% survival time of 800 days with surgery alone, which is much better than 414 days with surgery alone. Side effects include myelosuppression, gastrointestinal disorders, and nephrotoxicity, and cardiotoxicity, such as arrhythmia, which is not as common as in dogs. In addition, subcutaneous leakage of the drug may cause skin necrosis, so it should be administered with great care. Although anticancer drugs are an effective treatment, they are expensive, and since they are excreted in feces for 2.3 days after administration, they are carcinogenic to humans. In families with children, consultation is necessary, and treatment should be started after thoroughly discussing with the veterinarian and family whether proper management is possible.

How to prevent it?

The disease can be prevented with early sterilization. The incidence rate can be reduced to 91% or less when contraception is performed before 6 months of age, and to 86% or less within 1 year. After the age of 24 months, contraception is considered ineffective. If the effect of lowering the risk of mammary gland tumors is also expected, it is effective to perform contraceptive surgery before the age of 6 months when the first estrus occurs.

The rest is to touch the cat's body well every day. Mammary tumors are most often discovered when the owner brings her to the veterinarian because she has a lump in her breast. As mentioned above, the prognosis is often better when the tumor is detected at 2 cm or less, so early detection is also important.