Types of Breast Cancer

One of the most common types of breast cancer is infiltrating ductal carcinoma. However, there is a wide variety of different manifestations, which can be more aggressive.

Breast cancer is one of the most common tumors in women and is one of the leading causes of death. This pathology has many types depending on the region where it’s located and the cells that are affected. In this sense, different types of breast cancer have been described, each with different behavior and prognosis.

The cells most frequently affected in the mammary gland are those belonging to the epithelial tissue that covers the organ. In this way, most tumors acquire the name of carcinoma or adenocarcinoma, as they are glandular epithelium. However, the alterations can also appear in other glandular cells, which is why they acquire a different name.

Carcinoma in situ

This is the initial stage of all types of breast cancer, in which the tumor is localized and hasn’t invaded the surrounding tissues. All epithelial cells rest on a structure called the basal lamina, below which we can find connective tissue, blood vessels, and lymphatic vessels.

In general terms, we can say that it’s a carcinoma in situ when the basal lamina in the affected area is intact, so the tumor has not affected the connective tissue. Any carcinoma in situ has the probability of evolving into an infiltrating carcinoma, although the time in which this occurs can vary.

Ductal carcinoma in situ

Ductal carcinoma in situ is one of the two existing forms of carcinoma in situ, in which the alteration is found in the epithelium of the milk ducts. Studies show that it’s the most common form of in situ cancer, representing up to 90% of all cases.

It’s a localized condition, which hasn’t affected the basal lamina and there’s no formation of new blood vessels. This tumor is more likely to progress to a more aggressive invasive carcinoma if it isn’t treated in time. One of the possible causes of this type of breast cancer is the accumulation of genetic alterations for a long time.

Lobular carcinoma in situ

This is a less common form of in situ breast cancer, in which the lobes of the mammary gland and the terminal ducts are affected. The symptoms of breast cancer in this case aren’t so obvious, as it doesn’t usually generate a palpable mass, which can lead to an error in the diagnosis.

Fortunately, the progression of this tumor is very slow and it’s unlikely that an invasive carcinoma will develop from it. It isn’t usually considered as a disease itself by some specialists, but as a risk factor that increases the probability of developing other types of breast cancer.

Invasive ductal carcinoma (IDC)

Infiltrating ductal adenocarcinoma is one that affects the milk ducts and has penetrated the basement membrane of the epithelium, thus invading the nearby connective tissue. Multiple investigations have established that it’s the most common type of breast cancer and represents between 50 and 90% of all diagnosed breast carcinomas.

This carcinoma can affect women of any age, however, it’s more common after 55 years. The prognosis of this condition will depend on the characteristics of the tumor and the extent of the disease. In general terms, it’s good when the invasion is minimal and there’s no metastasis to distant organs.

Early diagnosis is essential when determining the prognosis of the disease. Prompt diagnosis and treatment will decrease the likelihood that the tumor will spread to other tissues through the lymphatic system or the bloodstream.

Invasive lobular carcinoma (ILC)

Infiltrating lobular carcinoma is one that appears in the lobes of the mammary gland and invades the surrounding tissue. It also has the ability to metastasize and invade distant organs such as the ICD. According to the American Cancer Society, its incidence is low, occurring in only 1 in 10 women with invasive breast cancer.

This type of cancer tends to be more difficult to detect through physical examination and mammography, because the signs and symptoms presented are less obvious. Fortunately, the prognosis of affected women is better than those diagnosed with CDI. In fact, experts estimate that they live up to 3 more years.

The causes and risk factors aren’t any different for this particular form of presentation, so genetic alterations and exposure to estrogens are decisive. Other factors such as smoking, alcohol consumption, and obesity also increase the likelihood of developing the disease.

Other invasive carcinomas

Both IDC and ILC are the most common invasive forms of this condition. However, there are other types of invasive breast cancer that are less common, which are differentiated by the histological pattern shown. These forms of presentation do not exceed 5% of all cases of breast carcinoma, among them the following stand out:

• Cystic adenoid
• Low-grade adenosquamous
• Medullary
• Papillary
• Micropapillary
• Mixed

Many of them have a better prognosis than IDC, however, micropapillary and mixed carcinoma are much more aggressive. In this sense, it’s vitally important to perform biopsies to determine the precise histological type.

Triple-negative breast cancer

This is a very particular form of presentation of breast cancer, which owes its name to the negative result of three different studies. In this sense, it lacks receptors for estrogens and progesterone, as well as the absence of overproduction of the hormone HER2.

Overall, triple-negative breast cancer is rare and is estimated to occur in up to 15% of all breast cancer cases. It’s more common in women under 40 years of age, African-American and with a BRCA 1 gene mutation. However, it can affect any woman.

Unfortunately, this is one of the most aggressive types of cancer, as it grows and spreads very quickly. Its therapy is very limited since many of the available treatments such as targeted therapy and hormonal treatment don’t help at all, so its prognosis is poor.

Inflammatory breast cancer

Inflammatory breast cancer is an invasive ductal carcinoma (IDC), which presents signs and symptoms that are very different from the usual ones. This is because cancer cells block the lymphatic drainage of the mammary gland, causing the breast to show signs of inflammation such as redness and enlargement.

One of the most indicative symptoms is the appearance of small dimples in the skin similar to those of the orange peel, which indicates lymphatic edema. The diagnosis of this form of presentation is a challenge, since it doesn’t generate the typical symptoms and simulates the presence of an infection such as mastitis.

This is one of the rarest types of breast cancer, in fact, the American Cancer Society estimates that it represents only between 1 and 5% of all cases of breast carcinoma. Unfortunately, most women are diagnosed in advanced stages of the disease when skin cells have already been affected, so their prognosis is worse than that of IDC.

Paget disease of the nipple

Paget’s disease of the nipple is another rare type of cancer, in which specific malignant cells called Paget’s cells affect the skin of the nipple, causing abnormal symptoms to appear in the area. The most frequently presented symptoms are nipple redness and nipple ulceration according to research.

Its incidence is very low compared to other types of cancer, and can reach up to 0.85% in some populations according to the cited study. This disease is usually diagnosed with some type of ductal carcinoma, either in situ or invasive. Fortunately, the prognosis of those diagnosed is very good, especially when the disease hasn’t spread.

Cancer diagnosis, in this case, is made based on the symptoms presented and on the observation of Paget cells in the lesion. Some imaging studies such as mammography and breast ultrasound can also be helpful in detecting the presence of another adjacent tumor.

Angiosarcoma of the breast

Angiosarcoma of the breast is a type of cancer that begins in the cells that line the blood vessels, called vascular endothelium. They can multiply abnormally and produce a very aggressive tumor, in fact, some specialists consider it to be the most lethal malignant breast tumor.

Fortunately, its incidence is low, and it’s estimated that it represents only 0.04% of all malignant breast tumors. The symptoms presented are characterized by the appearance of a purple nodule on the skin, as well as a lump in one or both breasts.

Breast angiosarcomas are a common complication of chemotherapy treatment for other types of breast cancer. In this sense, it’s possible to classify it as primary and secondary. The first case occurs when it appears in women who have never had the disease. It’s classed as secondary when it appears in women with a history of breast cancer.

Phyllodes tumors

These are tumors that appear in the connective tissue of the breast, so they can compress the blood and lymphatic vessels. They have a low incidence and represent less than 1% of all malignant breast tumors according to studies. Phyllodes tumors are usually benign, although 1 in 4 turns into cancer.

This tumor has a rapid growth, although, fortunately, it’s usually limited to the breast, so distant metastases are very rare. The tumor is more common in women between 41 and 49 years of age, especially in those with Li-Fraumeni syndrome.

Prompt treatment is important in all types of cancer

All existing types of breast cancer have unique characteristics that allow them to be differentiated from each other. The most frequent forms of presentation are ductal and lobular carcinoma, either invasive or in situ. However, the presence of other rare types of cancer should always be considered in order to achieve a timely diagnosis.

Something that all these tumors have in common is that life expectancy improves considerably if diagnosed and treated in the initial stages. In this sense, it’s vitally important to perform a breast self-examination periodically and to go to the specialist if you experience any strange symptoms.