Mammography-detected breast cancer in 40-49 year-olds has better prognosis
Based on a study of nearly 2,000 breast cancer patients, researchers at the Swedish Cancer Institute in Seattle say that, in women between the ages of 40 and 49, breast cancers detected by mammography have a better prognosis. The study appears in the March issue of Radiology.
“In our study, women aged 40 to 49 whose breast cancer was detected by mammography were easier to treat and had less recurring disease and mortality, because their cancer was found at an earlier stage,” said Judith A. Malmgren, Ph.D., president of HealthStat Consulting, Inc.
Dr. Malmgren and a team of researchers reviewed breast cancer patient data from a dedicated registry at the Swedish Cancer Institute’s community cancer center. The researchers analyzed data on 1,977 breast cancer patients between the ages of 40 and 49 who were treated between 1990 and 2008. The researchers looked at method of diagnosis (detected by mammography, patient or physician), stage at diagnosis (0-IV, confirmed by biopsy), treatment, and annual follow-up information, including recurrence of disease.
“Our goal was to assess the differences between mammography and non-mammography detected breast cancer, to determine whether earlier detection confers a treatment and morbidity advantage because the disease is found at an earlier stage,” Dr. Malmgren said.
The data analysis revealed a significant increase in the percentage of mammography-detected breast cancer over the 18-year period: from 28 percent in 1990 to 58 percent in 2008. Over the same period, patient- and physician-detected breast cancer declined from 73 percent of all cases in 1990 to 42 percent in 2008.
Breast cancer is the second most lethal cancer in women. (Lung cancer is the leading cancer killer in women.) The good news is that early detection and new treatments have improved survival rates. The 5-year survival rate for women diagnosed with cancer is 80%. About 88% of women diagnosed with breast cancer will survive at least 10 years. Unfortunately, women in lower social and economic groups still have significantly lower survival rates than women in higher groups.
Several factors are used to determine the risk for recurrence and the likelihood of successful treatment. They include:
Location of the tumor and how far it has spread
Whether the tumor is hormone receptor-positive or -negative
Tumor markers
Gene expression
Tumor size and shape
Rate of cell division
The good news is that women are living longer with breast cancer. Due to better treatment options, breast cancer mortality rates declined by about 25% since 1990. However, survivors must live with the uncertainties of possible recurrent cancer and some risk for complications from the treatment itself.
Recurrences of cancer usually develop within 5 years of treatment. About 25% of recurrences and half of new cancers in the opposite breast occur after 5 years.
“The shift toward more mammography-detected breast cancer cases was accompanied by a shift toward diagnosis at an earlier stage of disease that required less treatment,” Dr. Malmgren said.
Over the 18-year period, the number of breast cancers diagnosed at Stage 0 increased by 66 percent, while the number of Stage III breast cancers decreased by 66 percent. The majority of Stage 0 cancer cases were ductal carcinoma in situ (DCIS), a non-invasive cancer that is confined to a milk duct. The treatment of DCIS remains controversial, because not all experts agree that it is potentially life threatening.
The overall outlook
As with many other types of cancer, the outcome for breast cancer depends on how early or advanced it is when it is diagnosed. In other words, the stage of your cancer. Overall, in England and Wales, more than 80 out of every 100 people diagnosed with breast cancer live for at least 5 years after diagnosis. More than 70 out of every 100 people live for at least 10 years. The figures for Scotland are very similar.
It takes time to gather statistics and put them together. Doctors monitor women with breast cancer for many years. So the cancer statistics you see always relate to people diagnosed and treated some time ago. The outlook for breast cancer continues to improve. So it is important to bear in mind that figures for women treated more recently may be better.
Researchers have recently predicted (projected) survival rates so that we have more up to date figures. The first of these predictions were released in October 2005. They predict that 64 out of every 100 women diagnosed recently with breast cancer (64%) will live for at least 20 years. There is detailed information about these predicted survival rates in our breast cancer question and answer section.
If breast cancer is going to come back, it is most likely to do so within the first 2 years. With some other types of cancer, you are likely to be cured if your cancer has not come back within 5 years. Unfortunately, breast cancer can come back 10 or 20 years after you were first diagnosed. But, this is not common and the more time that passes since your diagnosis, the less likely it is that your cancer will come back.
The number of women dying from breast cancer has gone down significantly in the last 20 years in the UK. This is probably for a number of reasons. In particular, the UK breast screening programme is picking up breast cancer earlier and treatments continue to improve. Overall, for women whose breast cancers were picked up during screening, 93 out of every 100 (93%) lived for at least 5 years after their diagnosis. And 88 out of every 100 (88%) lived for at least 10 years after their diagnosis.
Dr. Malmgren said another key finding of the study was the extent of treatment patients received. Compared with women whose cancer was self-detected or discovered by a physician, patients whose cancer was detected using mammography were more likely to have breast-conserving treatment and less likely to have chemotherapy. Specifically, they were more likely to undergo lumpectomy (67 percent versus 48 percent), less likely to undergo modified radical mastectomy (25 percent versus 47 percent), and less likely to die of breast cancer (4 percent versus 11 percent).
“The benefits of breast cancer treatment are accompanied by significant harms,” Dr. Malmgren said. “Chemotherapy may have long-lasting toxic effects on a woman’s body, and mastectomy and reconstructive surgery are difficult and expensive operations that can have a significant effect on body image.”
The American Cancer Society and other medical organizations recommend that women should begin receiving annual mammograms to screen for breast cancer beginning at age 40. In 2009, the U.S. Preventive Services Task Force issued controversial new guidelines that eliminated the longstanding recommendation for routine mammography screening for women between the ages of 40 and 49, stating that the benefits of screening were potentially outweighed by the harms of screening, such as false-positive results.
“The objective of screening is to detect disease at an earlier, more treatable stage, which - based on our review - mammography accomplishes,” Dr. Malmgren said.
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“Impact of Mammography Detection on the Course of Breast Cancer in Women Aged 40 Years.” Collaborating with Dr. Malmgren were Jay Parikh, M.D., Mary K. Atwood, C.T.R., and Henry G. Kaplan, M.D.
The study was funded by the Kaplan Cancer Research Fund and the Cancer Surveillance System of the Fred Hutchinson Cancer Research Center.
Radiology is edited by Herbert Y. Kressel, M.D., Harvard Medical School, Boston, Mass., and owned and published by the Radiological Society of North America, Inc. (http://radiology.rsna.org/)
RSNA is an association of more than 48,000 radiologists, radiation oncologists, medical physicists and related scientists committed to excellence in patient care through education and research. The Society is based in Oak Brook, Ill.
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Linda Brooks
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630-590-7762
Radiological Society of North America