Breast Cancer Basics 1: ER, PR, and HER-2
Usually, breast cancer patients need to be definitively diagnosed by fine-needle (or core-needle) biopsy or by pathology after direct surgical resection. The pathology report will include an immunohistochemical analysis, in which several markers are crucial to the subsequent treatment of breast cancer patients; these markers are ER, PR, and HER-2, and they determine the patient's subsequent treatment plan.
The full name of ER is estrogen receptor. ER(+) indicates that the patient's estrogen receptor is positively expressed, and ER(−) indicates that it is negatively expressed. The full name of PR is progesterone receptor. PR(+) indicates that the patient's progesterone receptor is positively expressed, and PR(−) indicates that it is negatively expressed. A woman's breasts are affected by estrogen and progesterone throughout life, so breast-cancer patients who are positive for estrogen and progesterone receptors can curb the development of breast cancer through anti-estrogen/progesterone-receptor therapy.
The full name of HER-2 is human epidermal growth factor receptor-2; this is an oncogene in breast cancer patients. HER-2(+) indicates that the human epidermal growth factor receptor is positively expressed, and HER-2(−) indicates that it is negatively expressed.
Usually, the immunohistochemical results may also mark the above three markers as (1+), (2+), or (3+); this further indicates the degree of positive expression of these markers, with (3+) being strongly positive and (1+) weakly positive.
Patients positive for estrogen and progesterone receptors usually receive endocrine therapy. Human epidermal growth factor receptor 2 is an oncogene in breast cancer; HER-2-positive patients need trastuzumab (trade name Herceptin), a drug discovered to date that targets the inactivation of this gene. Trastuzumab is a humanized antibody used to target and block HER-2, thereby curbing the breast tumor in HER-2-positive patients.
If all three of the above are negatively expressed, we commonly call it triple-negative breast cancer. For triple-negative breast-cancer patients, both the commonly used endocrine therapy and trastuzumab are unsuitable. If all three are positively expressed, we commonly call it triple-positive breast cancer; triple-positive patients can simultaneously use endocrine therapy drugs and trastuzumab.
Does negative expression of ER, PR, and HER-2 mean the patient's condition is worse? The answer is not necessarily. Once triple-negative breast-cancer patients achieve good results through surgery and chemotherapy and maintain five years without recurrence, the probability of recurrence is relatively low. By contrast, patients with positive expression of one or more of ER, PR, and HER-2, after maintaining five years without recurrence following treatment, have a relatively higher probability of recurrence. Moreover, HER-2-positive patients, if they do not receive expensive targeted therapy, usually progress more rapidly. Fortunately, although Herceptin is expensive, it has been listed as a covered drug in our country's medical insurance, so the proportion patients with insurance need to pay out of pocket is limited.
Patients positive for estrogen and progesterone receptors need anti-estrogen/progesterone treatment, commonly called endocrine therapy. This treatment differs for premenopausal and postmenopausal women: premenopausal women generally use tamoxifen or raloxifene, while postmenopausal women generally use aromatase inhibitors. Premenopausal women who have used tamoxifen for two years can also switch to an aromatase inhibitor. Generally, endocrine therapy needs to be maintained for five years; less than five years of endocrine therapy means a higher risk of recurrence, while more than five years also brings higher risk, so its standard course is five years.
Tamoxifen has the side effect of causing osteoporosis and also carries the risk of causing uterine tumors in women; so in recent years, many premenopausal women have adopted a regimen of first taking tamoxifen for two years, then using an aromatase inhibitor (such as letrozole/Femara) for three years. Relevant research shows that this regimen achieves the same efficacy as five continuous years of tamoxifen, with relatively fewer side effects.
Many breast-cancer patients reject surgery and pathology examination; this practice is quite wrong. Through pathology examination rather than conservative TCM treatment, patients can clarify which type of breast cancer they belong to. If it is estrogen/progesterone-positive breast cancer, endocrine therapy can even achieve a curative effect. If it is HER-2-positive breast cancer, treatment with Herceptin will also have a good effect.
Tumor treatment requires comprehensive means, including Chinese medicine; most patients with localized breast cancer, after comprehensive treatment, have a survival time expected to exceed 15 years. Some patients receive pure TCM treatment from TCM doctors who know nothing about modern medical knowledge of breast cancer; the author believes this is an extremely high-risk thing, and the patient will lose years of life because of the ignorance of both themselves and the doctor they seek out.