Breast cancer: It is a common malignant tumor in women and is the leading cause of female cancer death in many countries. The incidence and mortality rate of breast cancer in some industrialized countries in Europe and America are increasing year by year. Although China is a low incidence area for breast cancer, about 13,000 women die from breast cancer every year. The incidence of breast cancer has surpassed that of cervical cancer to become the first cancer among women in China. Male breast cancer is rare, and its incidence rate is about 1% of women.
I. Epidemiology and Etiology
1. Epidemiology
Breast cancer rarely occurs before the age of 25. In the United States, the incidence and death of breast cancer continue to increase with age after 25 years old. In China, the peak incidence of breast cancer in women is during menopause (about 45-50 years old) and gradually decreases after 50 years old. The incidence rate continues to rise after menopause and reaches a peak at age 70. The mortality rate also increases with age.
2. Etiology
(1) Family history of breast cancer is one of the causes of the disease
The risk of breast cancer is 2-3 times higher among close female relatives (mothers, daughters, sisters) in the direct line of breast cancer patients than among women in general. Premenopausal women with bilateral breast cancer have a 9 times higher risk of developing the disease in the next generation of women.
(2) Women who do not have children are more likely to develop breast cancer than those who have children
The higher the number of pregnancies, the lower the risk of developing the disease. The risk increases when the first birth is over 35 years old. The risk increases as the age of first birth increases. The incidence of breast cancer in single women has been reported to be twice as high as that in married women. Breastfeeding does not increase the risk of susceptibility.
(3) Early menarche and delayed menopause
The risk of breast cancer increases when menarche is less than 13 years old and menopause is later than 50 years old.
(4) Ovariectomy patients
It has been reported that the risk of breast cancer decreases in those who undergo ovariectomy before the age of 35. Endocrine glands and shredder hormones are related to the occurrence of breast cancer. Estrogen and estradiol in estrogen are directly related, but there has been a debate on the role of hormone-containing drugs, such as compensatory estrogen therapy and oral contraceptives, on the occurrence of breast cancer, and the relationship between these drugs and breast cancer is still unclear.
(5) The relationship between benign breast lesions and breast cancer
It is still debated. It is generally believed that fibrocystic breast disease is no longer a risk factor, and the risk increases only when there are active changes in the biopsy breast tissue, such as hyperplasia and atypical hyperplasia.
(6) Breast cancer is related to nutritional intake
High-calorie and high-fat diet, especially excessive intake of animal fat, increases the risk of disease. Weight gain after menopause is an important risk factor for breast cancer. Alcohol consumption also increases the risk.
(7) Radioactive ionizing radiation is related to the development of breast cancer.
The risk increases with increasing dose of radiation exposure.
Some of the above-mentioned risk factors for the development of breast cancer are often found in breast cancer patients, and we call them risk factors. The presence of one or several risk factors does not necessarily mean that one will get breast cancer or is susceptible to it; it only means that the woman is at statistically greater risk than others. Without the above risk factors, breast can still occur and the definitive cause of breast cancer is not known. If the above risk factors are present, regular mammograms are recommended.
II. Anatomy and pathology
1. Anatomy
Before understanding the pathological classification, let’s briefly describe the anatomy of the breast.
The terms breast and mammary gland are commonly used in clinical practice. In addition to the mammary glands, fatty tissue and connective tissue make up the majority of the breast and play a supportive role. There are also nerves, blood vessels and lymphatic vessels in the breast.
The mammary glands are the functional tissues that produce milk. Each gland has 15-20 lobes and each lobe is divided into several lobules. Each lobe consists of a varying number of vesicles and terminal ducts connected to the vesicles which gradually converge into interlobular ducts and finally lead to the nipple through the large ducts of the lobes to deliver milk. Most of the breast cancers come from the epithelial cells of the lobules or ducts of the breast gland.
The lymphatic drainage of the breast is very rich. The lymphatic ducts are located between the lobes and around the lobes, and the lymphatic fluid flows through the lymphatic ducts to the regional lymph nodes. The lateral part of the breast, the middle part and the chest wall enter the anterior and middle groups of axillary lymph nodes, partly into the lateral group and finally into the subclavian group. The subclavian group has small lymphatic vessels leading to the supraclavicular lymph nodes. The medial part of the breast and periareolar lymph drain into the internal breast lymph nodes, and then into the supraclavicular lymph nodes or mediastinal lymph nodes.
2.Pathological types
Breast cancer has complex morphological structure and many types. Currently, breast cancer is divided into four categories: non-invasive cancer, early invasive cancer, special and non-special invasive cancer.
(1) Non-invasive carcinoma: including lobular carcinoma in situ and intraductal carcinoma. The lesions are early and not easily detected clinically, but often found by chance in biopsy specimens by the pathology department. Early infiltrative carcinoma includes early infiltration of lobular carcinoma and early infiltration of ductal carcinoma. The prognosis of these two types of cancer is significantly better than other types.
(2) Infiltrative specific types of cancer: papillary carcinoma, medullary carcinoma with massive lymphocytic infiltration, tubular carcinoma, adenoid cystic carcinoma, mucinous adenocarcinoma, sweat adenocarcinoma, squamous cell carcinoma, and Paget’s disease. It is less common and has a better prognosis than invasive non-specific carcinoma.
(3) Invasive non-specific carcinoma: invasive lobular carcinoma, invasive ductal carcinoma, simple carcinoma, sclerosing carcinoma, medullary carcinoma, adenocarcinoma. This kind of development is more common, and the prognosis is not good.
3.Receptor test
At present, the pathology departments of larger hospitals in China can do steroid hormone receptor determination. The results of the study have confirmed that breast cancer cells contain hormone receptors that can bind specific hormones such as estrogen and progesterone (ER and PR). The presence of progesterone receptors not only proves the existence of estrogen receptors on carcinogenesis, but also enhances this effect. Therefore, the determination of steroid hormone receptors is gaining more and more attention and is used to determine clinical endocrine therapy. The objective efficiency of endocrine therapy for estrogen receptor positive cases has been reported to be 55%-70%. Patients who are positive for both progesterone and estrogen receptors have the best results for endocrine therapy, with an efficiency rate of 75%, while patients who are deficient in both have poor results. This receptor test requires surgery or biopsy of the tumor specimen for examination, and the tumor tissue should be left in sufficient size. If the local hospital cannot do this test, it is better to keep the specimen wax block for transfer.
Natural course and development
The natural course of breast cancer is long. It takes about 7-8 years for a tumor to proliferate and reach 1 cm in diameter from the time a breast cell becomes malignant. Therefore, we should insist on regular examination of the breast for early detection and treatment.
Breast cancer expands directly to the surrounding area, invading the upper skin and blocking the lymphatic vessels, causing indentation of the breast skin, lymphedema and orange peel-like changes; invading to the deeper part and the pectoral muscle and ribs, the cancer is fixed with the chest wall.
Breast cancer can also spread by lymphatic tract and bloodstream. Lymph nodes are the first barrier to prevent the spread of cancer cells. If the lymph nodes cannot destroy the escaped cancer cells, the regional lymph nodes will be the first to metastasize. The axillary lymph nodes are involved and further invade the supraclavicular lymph nodes; the parasternal (internal breast) lymph nodes may also be involved; in more advanced stages, metastasis of mediastinal lymph nodes may also occur. After passing through the lymphatic barrier, cancer cells can invade the veins and metastasize bloodstream. Bloodstream metastasis of breast cancer is most common in bone, lung, liver and brain.
IV. Early detection
At present, we cannot prevent breast cancer, and although the treatment methods are constantly improving, they do not have much impact on the survival rate of breast cancer. Only in the measures of early detection and early treatment of breast cancer can we effectively improve the cure rate greatly and reduce the mortality rate, which is far-reaching.
The means of early detection of breast cancer are: general population screening, breast self-examination, doctor’s examination and mammogram.
1.Self-examination of breast
In North America and Western Europe, breast cancer screening has been carried out well and many early breast cancers have been detected and cured. In China, due to the economic backwardness and low literacy level of the population, breast cancer screening is difficult and only carried out on a small scale. Therefore, breast self-examination, especially for women with high-risk factors, should be paid more attention to breast self-examination and should be carried out once a month. It is better for amenorrheic women to fix one day a month so as not to forget. In women with normal menstruation, many normal breasts also have some nodules due to the influence of estrogen, so it is best to choose 3-4 days after menstruation is clean for examination, when the breasts are mostly loose and soft.
Breast examination should be done in a brightly lit place, in a sitting or standing position, with the top removed so that both breasts are fully exposed, with both arms hanging down and looking into a mirror.
(1) Visual examination: first look at whether the bilateral breasts are similar in size and symmetrical in outline; whether there is local bulge or depression; whether the skin of the mammary glands is wrinkled, broken, desquamated and changed in color; whether the nipples on both sides are on the same level; whether there is nipple depression, nipple overflow, etc. While carefully observing, both arms are raised and crossed behind the neck to observe any changes in the shape of the breast and any local skin elevation or depression.
(2) Palpation: Cross your arms with your shoulders and elbows slightly forward and relax. Lower the right hand and examine the left breast by touch with the right hand. Touch with the palm surface of the fingers, do not grasp and pinch the breast, and touch the inner upper, outer upper, outer lower and inner lower quadrants of the breast in a clockwise direction, and finally the areola and nipple central area, making sure to feel the entire breast all over. The lump in the lower part of the breast is often covered by the sagging breast, so you can hold the breast up with one hand and touch it with the other, better when lying down. At the same time, we should pay attention to the touch of the ipsilateral axilla, as some breast cancers have lymph node metastasis at an early stage.
(3) Check the right breast by palpation.
If you find abnormal breast appearance, nodules or lumps during breast self-examination, you should go to the hospital immediately for further examination. Readers do not have to worry too much, according to statistics from the United States, about 80% of the abnormal changes found in the breast self-examination belong to the benign range.
2. Doctor’s examination
This is a mammogram done by a doctor with professional experience. The method is similar to the above-mentioned breast self-examination method, but the doctor’s judgment is more objective.
3.X-ray of the breast
It can exclude most benign lesions and detect some early lesions of breast cancer that cannot be detected clinically.
V. Consultation examination
When patients go to the hospital, the first thing they need to do is the doctor’s examination and a series of auxiliary examinations.
1. Palpation by the doctor
The procedure is basically the same as that of breast self-examination. The doctor carefully palpates the bilateral breast and the lymphatic drainage area. The diagnosis is not difficult for cases with typical clinical manifestations, but for some cases that cannot be easily distinguished from benign lesions, the doctor will give further examinations. Each examination by the doctor should record in detail the size, shape, hardness, mobility and relationship with the skin and surrounding tissues of the lump found, so that it can be compared in future review.
2.X-ray of the breast
Nowadays, mammography is commonly used, which is a safer way to examine the lump by using a very small amount of radiographs, and the amount of X-rays received by the subject is extremely low. Mammography can identify some benign and malignant lesions and find some small tumors.
3.Thermal image examination
There are various methods of thermal image mammography, but the two commonly used in China are liquid crystal and far infrared thermal image. Using the different thermal radiation of breast tissue and tumor tissue, the sensing probe collects thermal radiation and images. The tumor site is imaged by showing the thermal area. The disadvantage of thermal images for breast cancer diagnosis is that the false positive and false negative rates are high, and the detection rate of small breast cancers in deep areas is too low. Therefore, thermal imaging is no longer used as the main means to diagnose breast cancer.
4.Near infrared scan
It is a breast examination method developed in recent years. It uses the principle of infrared light to show different shades of gray through different tissues of the breast to show breast lumps. Breast cancer is often rich in local blood flow and infrared light can show this better and help to distinguish the nature of the lump. However, there are some false positives in infrared scan for breast cancer diagnosis.
5.Computed tomography (CT) and magnetic resonance imaging (MR)
CT and MR are usually not used for breast scan, but mostly used for the diagnosis of lung metastasis and liver metastasis in advanced breast cancer.
6.Exfoliative cytology examination
It is mainly used in cases with nipple overflow. Cytological examination with nipple scrapings or smears of nipple discharge is a simple, painless and harmless method. It is also more reliable for diagnosis. It is reported that the positive rate of Paget’s disease is 70%-80%, and the positive rate of early intraductal carcinoma is 50%.
7.Needle aspiration cytology examination
It is a simple method to directly puncture the swelling with an empty needle and use negative pressure to aspirate the internal components of the swelling for cytological examination by smear. However, the operation should pay attention to prevent tumor dissemination, and when choosing the needle site, pay attention to the eye of the needle should be within the scope of surgery. If the needle aspiration cytology test confirms cancer, surgery should be performed as soon as possible.
If the result of needle aspiration cytology is positive, the diagnosis of breast cancer is basically established. If the test result is negative and there is a high clinical suspicion of breast cancer, biopsy should be done.
8.Biopsy
Surgical biopsy is a reliable diagnostic tool, and its diagnostic accuracy rate is reported to be over 98%. Unless the lump is very large, excisional biopsy should be done in general. The excision should cover the entire lump and a little of the surrounding normal breast tissue. The excisional biopsy should preferably be performed on the operating table; the lump should be sent for frozen section immediately after excision, and if the pathology is benign, the surgery is over; if it is malignant, further radical surgery is performed. If the pathology is confirmed to be malignant after minor outpatient surgery, it is best to perform radical surgery as soon as possible, and the shorter the interval, the better.
VI. Diagnosis
The diagnosis of breast cancer is not difficult when clinically encountering a breast lump with typical manifestations, such as a large lump with hard texture, poor mobility and unclear border; sunken nipple, overflowing blood; orange peel-like skin changes, skin rupture, tumor nodules, etc. Doctors will recommend immediate surgical removal. If the lesion presentation is atypical, further examination will be recommended, including mammography; needle aspiration cytology; near infrared scan, etc. If several tests are positive, the diagnosis of breast cancer is basically established. If only one positive result is found, there is still a possibility of cancer. Close follow-up for a few weeks or months is recommended, and if necessary, excisional biopsy will be done to clarify the diagnosis.
Few patients are first found to be metastatic lesions in axillary lymph nodes or lung, bone, liver, etc. Careful examination of breast and axillary lymph nodes, chest X-ray, CT, bone scan and other examinations should be performed to clarify the primary foci and metastases.
VII. Staging
Clinical staging should be determined at the same time of breast cancer diagnosis. The so-called staging is simply to determine the extent of the disease at the time of breast cancer diagnosis, so as to facilitate treatment planning and estimation of prognosis and efficacy. The TNM staging of breast cancer is now commonly used and is highly specialized.
Stage I: The tumor is confined to the breast tissue, its length and diameter do not exceed 2 cm, no adhesion to the skin, no axillary lymph node metastasis, and no hematogenous metastasis.
Stage II: There are several scattered movable lymph nodes in the ipsilateral axilla without evidence of primary tumor or the tumor length diameter does not exceed 2 cm, which is the stage IIa; there are movable lymph node metastasis in the ipsilateral axilla and the tumor length diameter is 2-5 cm, or the tumor length diameter is more than 5 cm without axillary lymph node metastasis, which is the stage IIb. There is no hematogenous metastasis in this stage.
Stage III: ipsilateral axillary lymph node metastasis, lymph nodes fused with each other or adhered to surrounding tissues, no evidence of primary foci or tumor not invading skin or chest wall regardless of size, but with axillary lymph node metastasis, all belong to stage IIIa; primary breast tumor, regardless of size, directly invading skin or chest wall, regardless of whether there is lymph node metastasis in ipsilateral axilla or internal breast lymph node metastasis belongs to stage IIIb. However, there is no hematogenous metastasis.
Stage IV: Regardless of the primary foci and ipsilateral axillary lymph nodes, as long as there is distant metastasis, it belongs to this stage (including ipsilateral supraclavicular lymph node metastasis).