Do you notice that your cat has swollen or lumpy breasts? It could be a symptom of breast cancer, the third most common neoplasm in this species. The early sterilization of cats is an important preventive measure and the vast majority are very aggressive cancers called adenocarcinomas, so the earliest possible detection, together with the complete mastectomy operation, is essential to prolong the survival of cats to a certain extent. our cat.
What is mammary cancer in cats?
Breast cancer is the transformation of the normal cells of the mammary gland into tumor cells that have a greater ability to multiply and invasion of nearby or distant tissues via hematogenous or lymphatic routes.
In cats, mammary tumors are the third most common type of cancer, preceded by lymphoma and skin tumors. Malignant tumors are much more common than benign ones, with a percentage of 90% and a high mortality Adenocarcinomas are the most frequent malignant tumors in cats. In addition, around 35% of breast tumors at the time of diagnosis already have metastases in nearby tissues. This metastasis can occur at a distance, affecting various organs, occurring in more than 80% of cases in the lung.
For more information, you can read this other article on our site about Cancer in cats - Types, symptoms and treatment.
Causes of mammary cancer in cats
Among the causes that can lead to breast cancer in cats we find genetic factors, carcinogenic agents, some viruses and environmental contaminants. However, the most likely cause is hormonal, because breast tumors are hormonally dependent, which means that most have estrogen receptors and progestogens, hence early sterilization is the best prevention.
Prolonged therapy with progestogens increases the risk of presentation, since the main mechanism by which progesterone or progestogens induce tumors is the overproduction of growth hormone in the mammary gland, which will directly stimulate the growth of the gland and indirectly through the growth factor linked to insulin, which plays a determining role in the proliferation of cells and their transformation into neoplastic cells.
Feline Breast Cancer Risk Factors
A cat's risk of breast cancer is increased:
- As her age increases
- If they are not sterilized.
- If you sterilized late.
Any breed can be affected, but some studies indicate that Siamese cats have twice the risk of suffering from them and in European cats it is also usually more frequent.
Symptoms of mammary cancer in cats
Female cats have a total of eight mammae divided into two cranial and two caudal nerves. Breast tumors can appear isolated as a single, well-circumscribed, mobile mass or infiltrative-type growth to deep sites that have the potential to ulcerate and cause secondary infection. It is also common for the same affected breast to present multiple nodules, although it is normal for several breasts to be affected. About 60% of cats have more than one tumor when diagnosed. Nearby lymph nodes are also often affected.
In cats, the aggressiveness of the mammary tumor is much higher than in dogs, so that the tumor cells rapidly invade the lymphatic circuit, metastasizing to distant organs. The clinical signs indicative of mammary tumor in cats are:
- Lump in one or several breasts.
- Growth of these lumps.
- Ulceration of tumors.
- Breast infections.
- Lung or other organ conditions if the tumor has spread.
- Weightloss.
- Weakness.
Feline Breast Cancer Diagnosis
The usual diagnostic procedure for this disease includes blood tests, urine tests and chest x-rays. Because it normally occurs in older cats, it is also important to measure T4 to see the status of the thyroid.
Although the vast majority of mammary tumors in cats are malignant, a differential diagnosis should be made for the mammary lesions described abovewith other pathologies that non-neutered cats may present: fibroadenomatous hyperplasia, pseudopregnancy and gestation.
The feline breast tumor staging system is based on the size of the primary tumor by measuring the diameter of the mass (T), involvement of nearby lymph nodes (N) and metastasis in distant organs (M). All the mammary glands and surrounding tissue should be palpated, palpation and cytology of their regional lymph nodes, chest X-rays performed in various projections to assess possible pulmonary metastasis and abdominal ultrasound to assess metastases in abdominal organs.
Stages of mammary cancer in cats
The stages of mammary cancer in cats are:
- I: Lumps smaller than 2 cm (T1).
- II: 2-3 cm lumps (T2).
- III: Lumps larger than 3 cm (T3) with or without regional metastasis (N0 or N1) or T1 or T2 with metastasis regional (N1).
- IV: distant metastasis (M1) and the presence or absence of regional metastasis.
Treatment of mammary cancer in cats
Because mammary adenocarcinomas in cats are invasive and have a high rate of lymphatic involvement, aggressive treatment is required This treatment will consist of a breast removal surgery, also called a mastectomy that can be complemented with chemotherapy and radiotherapy. Radiotherapy is a local treatment that in cats can be effective in preventing tumor recurrence.
How is the mammary tumor operation in cats?
Mastectomy in cats is more aggressive than in dogs, because the entire affected mammary chain must be performed It is contraindicated only when the disease is very advanced and there are already metastases in distant organs, so that a complete mastectomy will be performed on one side if the affected breasts are in a single chain or complete bilateral if the affected breasts are distributed by both mammary chains. In addition, it must be completely removed with a few wide margins which are key to reducing cancer recurrence in the area and increasing survival times.
The affected lymph nodes must also be included in the mastectomy The inguinal is removed together with the caudal mammary gland and the axillary is removed only if it is enlarged or metastasis has been detected in the cytology. Once extracted, samples should be taken to send to histopathology to diagnose the type of tumor the cat has.
In the postoperative period of mastectomy in cats, analgesics and antibiotics are necessary to control pain, inflammation and possible infections produced. The first week is the most annoying, especially the complete bilateral ones. It may take several days for your cat to increase her mood, appetite and vitality. They should be given a Elizabethan collar so they don't lick the area and open the stitches. On the other hand, the possible complications are:
- Pain.
- Inflammation.
- Infection.
- Necrosis.
- Self-trauma.
- Suture rupture.
- Hindlimb edema.
Chemotherapy for breast cancer in cats
Based on the principles of oncology, adjuvant chemotherapy is recommended in cats with clinical stages III and IV or in cats with Stage II or III malignant tumors It is performed after removal of the tumor to delay recurrences, lengthening the remission period and delaying the appearance of metastases. every 3-4 weeks is usually administered, giving a total of 4-6 cycles. The side effects that may appear in a cat undergoing chemotherapy will be: anorexia and anemia and a decrease in white blood cells due to myelosuppression.
It may also be interesting to add a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase type 2 (COX-2), such as firocoxib or meloxicam, as these tumors have been shown to express COX-2. On the other hand, different chemotherapy protocols have been described for feline mammary tumors:
- If we have stage III or IV breast cancer: doxorubicin (20-30 mg/m2 or 1 mg/kg intravenously every 3 weeks) + cyclophosphamide (100 mg/m2 for 3 days every 3 weeks orally).
- With surgery + carboplatin (200 mg/m2 intravenous every 3 weeks, 4 doses) studies showed a median survival of 428 days.
- Cats with surgery and doxorubicin in tumors smaller than 2 cm demonstrated a median survival of 450 days.
- With surgery and doxorubicin, a survival of 1998 days.
- With surgery, doxorubicin and meloxicam, a survival of 460 days was observed.
- With surgery and mitoxantrone (6 mg/m2 intravenous every 3 weeks, 4 doses) a survival of 450 days was determined.
It is usually accompanied by food supplements, antiemetics and appetite stimulants to prevent weight loss and remedy symptoms. At the same time, if the cat presents some type of organic failure, it must be treated.
Feline Breast Cancer Prognosis
The forecast is always reserved. The mean survival time from diagnosis to death of the cat is 10-12 months Early diagnosis and early mastectomy are key factors in extending the survival time.
The prognosis will always be worse the larger the diameter of the tumor Those with a small diameter will show longer periods of remission and longer of survival. The presence of distant metastases is always indicative of a poor prognosis.
In this way, if you notice any change in your cat's mammary glands, you should go to the vet to find out as soon as possible if we are facing a breast cancer or other breast pathology. As we have mentioned, the progression of malignant breast cancer is devastating, since in most cases it will invade our cat's lungs, making it difficult for her to breathe properly, as well as other parts of her body, and finally will cause your death
Prevention of mammary cancer in cats
The best prevention of mammary cancer in cats is early sterilization, before their first heats,because they will greatly reduce the chances of suffering from it, which is essential, since the life expectancy of a cat with breast cancer is very low, even with treatment.
If you get sterilized after your first year of life, even if you don't have a reduction in the probability of breast cancer, you can avoid others such as pyometras, metritis and ovarian or uterine tumors.
Early neutering considerably reduces the future occurrence of mammary cancer in cats, so that:
- Decreases by 91% if done before 6 months, that is, they will only have a 9% chance of suffering from it.
- After the first heat the probability will be 14%.
- After the second heat the probability will be 89%.
- After the third heat the risk of breast cancer is not reduced.
