Breast tumor
As mammary tumors are benign and malignant tumors of the mammary gland of man or those of the mammary gland called with animals. In humans, women are mainly affected, men much less often. Today pathologists only refer to real neoplasms (uncontrolled new tissue formation from atypical cells) as a tumor . In general medical parlance, non-neoplastic masses and tumor-like changes are also called this.
Benign breast tumors and tumor-like lesions in humans are for the most part fibroadenomas or fibro cystic changes. Among animals, mammary tumors are regularly observed in domestic animals and are highly variable with regard to their biological behavior .
human
See also : breast cancer
Fibrocystic changes arise in the glandular and duct epithelium due to the changing hormonal influences in the female cycle. Cysts arise from enlarged milk ducts and glandular lobules (lobules) and can be a few millimeters to several centimeters in size. Most of the palpable "lumps" in the chest are cysts. The cyst wall consists of atrophied glandular epithelium, which degenerates about as rarely as normal glandular tissue. So cysts are not a risk factor for the development of breast cancer.
The connective tissue ( fibrotic ) remodeling processes and calcifications of the glandular lobules are called sclerosing adenosis . The microscopic examination of such areas often also shows hyperplasia (increased number of cells) in the epithelia, without this being a precursor to cancer.
Only the so-called atypical hyperplasia of the ducts ( atypical ductal hyperplasia , ADH) or the lobules carries a measurably increased risk of degeneration. Microscopically, it can be recognized by an irregular, sieve-like filling of the ganglumen with slightly irregular cells. The atypical hyperplasia is classified as a precancerous condition and is usually surgically removed. The transition from atypical hyperplasia to real in-situ carcinomas ( LCIS , DCIS ) is fluid. In-situ carcinomas are characterized by a complete abolition of the normal layer structure of the epithelium.
Nipple papillomas ( milk duct papillomas ) are macroscopically visible hyperplastic growths on the inner wall of a large milk duct near the nipple, which can be felt as nodules. They can degenerate and are therefore also operated on as precancerous stages. Papillomas are the leading cause of bleeding from the nipple. They are most common in pre-menopausal women.
Nipple polyps are small, benign growths on the nipples.
Fibroadenomas are benign growths of branched terminal ducts, lobules, and connective tissue without a tendency to degenerate. They are the most common solid knots, especially in younger women under 40. If they do not change for several years or are confirmed by a biopsy, they do not need an operation.
Phyllodes tumors are similar to fibroadenomas, but they grow very quickly. Your connective tissue component degenerates in approx. 20%. Phyllodes tumors must therefore be removed.
Hamartomas are mixed tumors made up of scattered embryonic cells, which presumably develop in childhood and are benign. They characteristically contain glandular tissue, fat and connective tissue.
Purely connective tissue tumors of the breast are rarer. They can develop all types of tissue: benign lipomas , myomas , fibromas , hemangiomas and various malignant sarcomas also arise in the mammary gland. Also lymphomas and metastases of tumors in other organs are occasionally found.
Large, palpable nodules are predominantly benign breast tumors and cysts , while only 8% make up malignant carcinomas or precursors. The small foci found in the mammography screening are also predominantly benign.
animal
dog
Breast tumors are among the most common neoplasms in dogs, with an incidence of around 200 diseases per 100,000 non-neutered bitches. They rarely occur before the age of four, the animals most frequently affected are older than seven years, with most cases occurring between the ages of 10 and 14 years. A castration of the animal before the first heat prevents the formation of Gesäugetumoren almost completely at a castration until the age of 2.5 years, the less likely a subsequent tumor formation in a quarter. Castration at a later point in time no longer has any influence on the development of malignant neoplasms, but the incidence of benign tumors is lower than in intact animals. The use of sex hormones that prevent heat (especially combinations of gestagens and estrogens ) increases the risk of developing benign tumors. Earlier pregnancy has no influence on tumor development.
Only 20 to 40 percent of canine mammary gland tumors are malignant. These are predominantly different types of carcinoma , sarcoma is present in around 3 percent of cases , and a mixed type ( carcinosarcoma ) is even rarer . Adenomas are the most common benign tumors. In addition, unclassified tumors and dysplasias or hyperplasias of the breast (fibroses, cysts, ductal hyperplasia, lobular hyperplasia, gynecomastia ) are found.
The metastasis of malignant tumors is predominantly lymphogenous into the regional lymph nodes or haematogenously into the lungs . Metastases to other organs are rather the exception as a diagnostic criterion (less than 10 percent of cases with organ metastases have no corresponding lung findings). A clinical picture similar to the bone metastases in the distal limbs, which are relatively common in cats, can be caused by a paraneoplastic syndrome ( acropachia ).
The therapy of choice is surgical therapy. Depending on the individual situation of the animal concerned, a lumpectomy or mastectomy is performed . A cytological examination carried out preoperatively does not provide any reliable indication of the dignity of the tumor. Chemotherapy with doxorubicin carried out during surgery has shown success in individual cases, but an influence on life expectancy has not been proven with certainty. The same applies to the use of radiation therapy.
cat
Mammary tumors in cats make up about 5–18% of all tumors in this species. They behave much more aggressively than dogs. Around 90% of mammary tumors are malignant, 90% of which are adenocarcinomas . Like human breast cancer, they preferentially metastasize to the bones and lungs. In cats, mammary cancers are so common that if they are lameness, bone metastases from mammary cancers must be considered as the cause, since a preferred target of the metastases is the tip of the limbs. Intact queens are most often affected, 4% of breast tumors occur in male cats. The mean age of onset is between 10 and 12 years. Siamese cats are particularly affected. Hormone treatments promote the development of breast tumors. Early castration reduces the risk of development drastically. The risk of metastasis depends on the size of the tumor. In tumors <3 cm, metastases are not yet detectable in just under 80% of the animals concerned; with a tumor size> 3 cm, metastases have already formed in half of the animals.
Due to the high risk of metastasis, early removal of the affected milk ridge (radical mastectomy) is the treatment of choice. In old and otherwise sick animals, only the tumor can be removed palliatively. Doxorubicin is the agent of choice for chemotherapy, but it is only of limited effectiveness as an adjunct therapy to mastectomy. For tumors <2 cm, the mean survival time after radical udder removal is over 3 years, for tumors> 3 cm it drops to 4 to 6 months.
Feline fibroadenomatosis is an essential benign differential diagnosis, sometimes with impressive proportions .
Guinea pig
Mammary tumors in guinea pigs usually have a malignant character. The tumor formation occurs preferentially in middle-aged to old animals, whereby male animals are more frequently affected. As a rule, they can be surgically treated well.
rat
30 to 57 percent of the total population become ill. About 80% of the cases are benign adenomas or fibroadenomas, which can become very large and thus negatively affect the animals' locomotion. Intact females are affected in 90% of cases. The formation can be reduced through careful, energetically limited feeding in the first 7 weeks after weaning and presumably through castration of female animals. 20% of cases are malignant adenocarcinomas, which, however, are slow to metastasize.
The breast tumors of rats and mice , which are used in research into breast cancer, are generally benign and do not form metastases. However, attempts are being made to develop metastatic mammalian tumors in rats and mice for research purposes. The treatment of choice for mammary cancer is surgery. In the case of high malignancy , subsequent chemotherapy is indicated, with doxorubicin- based chemotherapy protocols often being used .
Rabbits
Especially female, pluriparous animals aged 3 to 4 years are affected by invasively growing adenocarcinomas. An early ovariohysterectomy lowers the risk of developing a malignancy in rabbits.
Web links
- About canine mammary cancer (PDF file; 3.42 MB)
- Mammographic microcalcification analysis and histology of breast cancer
References and literature
- ↑ breastdiseases.com ( Memento of July 10, 2013 in the Internet Archive )
- ^ Gynecologists on the Net: Breast Diseases .
- ↑ Fragor.xyz: Benign breast problems .
- ↑ Aiello EJ, et al .: Rate of breast cancer diagnoses among postmenopausal women with self-reported breast symptoms. J American Board of Family Practice 2004 (17): 408-15
- ↑ JM Dobson, S. Samuel, H. Milstein, K. Rogers, JL Wood: Canine neoplasia in the UK: estimates of incidence rates from a population of insured dogs. In: The Journal of Small Animal Practice. Volume 43, Number 6, June 2002, pp. 240-246, ISSN 0022-4510 . PMID 12074288 .
- ↑ a b Martin Kessler et al .: Breast cancer in cats - clinical findings and course of therapy in 34 patients. In: Kleintierpraxis 59 (2014), pp. 245–251.
- ^ A b Esther Lautschen: Feline mammary tumors . In: Veterinärspiegel Issue 1 2017, pp. 9-14.
- ^ JE Harkness and JE Wagner: Specific diseases and conditions. In: JE Harkness and JE Wagner: The Biology and Medicine of Rabbits and Rodents. 4th ed., WB Saunders, Philadelphia, PA 1995, pp. 627-651.
- Martin Kessler, oncologist for small animals , Parey Verlag 2005
