The expression of progesterone receptors coincides with an arrest of DNA synthesis in human breast cancer

Article Abstract:

Hormonal therapy is effective in only one third of breast cancer patients. Research has demonstrated that the response to hormonal therapy is largely determined by the presence of hormone receptors on the breast cancer cells. In tumor tissue that lacks both estrogen and progesterone receptors, the response rate is about 10 percent. For tumors that are estrogen receptor-positive, but lack the progesterone receptor, the response rate is about 30 percent. When both estrogen and progesterone receptors are present, the response rate jumps to 80 percent. There are too few patients with cells positive for only the progesterone receptor to draw any conclusions about such cells. It is clear, however, that the progesterone receptor is an important determinant of response to hormonal treatment. Varying hypotheses have been put forward to explain the variations of receptor expression and the variations of response to antiestrogen treatment. However, it has been observed clinically that if a patient with estrogen receptor-positive cells relapses after treatment, the cells still express estrogen receptor. The authors suggest that this supports the notion that the original tumor cells lack both receptors, but in the course of tumor growth some cells differentiate to express the estrogen receptor first, and then both progesterone and estrogen receptors. To examine this idea, researchers attempted to correlate the proliferative capacity of breast cancer cells with the expression of hormone receptors. It was found that the cell populations that expressed neither receptor incorporated more radioactive thymidine, indicating a higher rate of DNA synthesis. Cells that possessed the progesterone receptor had a thymidine labelling index of 0.21, while the cells that lacked the progesterone receptor had a thymidine labelling index over four times greater, at 0.94. The indices of cells with and without the estrogen receptor were intermediate at 0.53 and 0.74, respectively. These results indicate that the expression of progesterone receptors is associated with a reduction in DNA synthesis and therefore a reduction in proliferation. The results also suggest that the population of cells expressing the estrogen receptor is different from, but overlaps with, the population of cells expressing the progesterone receptor. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Hormone therapy, Chemotherapy

---

Steroid-hormone receptors in nonpalpable and more advanced stages of breast cancer: a contribution to the biology and natural history of carcinoma of the female breast

Article Abstract:

Since researchers first identified the presence or absence of hormone receptors on breast cancer cells, large numbers of observations have been made concerning the prognostic value of these hormone receptors. A trend has been noted in which more advanced cancers are more likely to be negative for estrogen and progesterone receptors. This has caused some conjecture that virtually all breast cancers are positive for these receptors at the time of the cancer's inception. To provide more information on this question, an investigation was performed on 557 biopsy and surgical breast cancer specimens, including 52 biopsies of nonpalpable cancers (which are detected by mammography an estimated three years sooner than they would otherwise be found). If the prevailing notion is correct, then the nonpalpable cancers should have a higher proportion of cells positive for the hormone receptors. These nonpalpable cancers represent the earliest stage of human breast cancer that can be studied. As predicted, these early cancers were more likely to be positive for the receptors than the later stages; 84 percent were positive for the estrogen receptor and 79 for the progesterone receptor. This is in contrast to 65 and 63 percent positive estrogen and progesterone receptor status, respectively, by the time the cancers became palpable. The trend toward high receptor positivity with decreasing tumor stage is true for both premenopausal and postmenopausal women. The evidence supports the notion that all breast cancers may begin life positive for both the estrogen and progesterone receptors. The authors point out that by the time a nonpalpable tumor becomes large enough to be detectable over half its life is complete. At a size of about 5 millimeters, the discernable size on mammography, the cancer has already undergone about 22 cell doublings. Without exception, 14 more doublings would be lethal. (Consumer Summary produced by Reliance Medical Information, Inc.)

---

Comparison of estrogen receptor and epidermal growth factor receptor content of primary and involved nodes of human breast cancer

Article Abstract:

Breast cancer is a hormone-dependent cancer. Epidemiological studies suggest that the female sex hormone estrogen is involved with both causing the cancer and in stimulating its early proliferation. Further along in its development, the cancer may lose its responsiveness to estrogen, an event associated with a poorer prognosis. The response of breast cancer cells, as well as healthy cells, to estrogen requires the interaction of the hormone with specific receptor molecules. Examination of the role of receptors in the development and progression of breast cancer has revealed a high frequency of receptors for a growth factor called epidermal growth factor (EGF), and it is believed that this factor may be important in stimulating the growth of breast cancers. For these reasons, a study was conducted to examine both receptors, estrogen, and EGF in a series of 19 breast cancer specimens and breast cancer-containing lymph nodes from the same patients. It was found that all 12 specimens that were positive for estrogen receptor also had estrogen receptors on the cancer cells in the lymph nodes. However, both the absolute amount of estrogen receptor and the fraction of cells with estrogen receptors were less for the lymph nodes. If the primary tumor was devoid of estrogen receptors, so were the cells in the lymph nodes. The pattern of EGF receptors was somewhat complementary to this. Among the patients with estrogen receptor-positive cells, a greater fraction of cells in the lymph nodes had EGF receptors and the total receptors per cell was greater. However, among the patients without estrogen receptors, no differences in the EGF receptors between the primary cancer and the cancer cells in the lymph nodes were found. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Cell receptors, Epidermal growth factor, Epidermal growth factors

Similar abstracts:

• Abstracts: Altered expression of the retinoblastoma gene product in human sarcomas. Association of the Lewis blood-group phenotype with recurrent urinary tract infections in women
• Abstracts: Prognostic significance of steroid receptors measured in primary metastatic and recurrent endometrial cancer. Blood flow characteristics of ovarian tumors: implications for ovarian cancer screening
• Abstracts: Success of reentry into anesthesiology training programs by residents with a history of substance abuse. Physician, cherish thyself: the hazards of self-prescribing
• Abstracts: New approaches may aid patients with inflammatory bowel disease. Largest-ever antismoking effort aims to form grass-roots coalitions
• Abstracts: B-cell lymphoproliferative disorders after bone marrow transplant: an analysis of ten cases with emphasis on Epstein-Barr virus detection by in situ hybridization

This website is not affiliated with document authors or copyright owners. This page is provided for informational purposes only. Unintentional errors are possible.