Mammograms are considered the best screening test for breast cancer, but even 1 low-energy mammography radiation is sufficient to cause DNA mutations. It heightens the risk of breast cancer by about 1% in women before menopause. Tumors in denser breasts of younger women may still go undetected by mammography. Women below 40 should carefully weigh its benefits against its risks.
Mammography is a diagnostic and screening tool that uses low-dose x-rays to examine the human breast and detect cancer. The primary goal of mammography – the most common method of screening right now – is the early detection of breast cancer. But, ironically, the toxic effects of mammogram radiation are now considered a significant contributing factor in the development of breast cancer. Many recent studies clearly show that mammography procedures for screening of breast cancer may be causing women more harm than good.1
How Can Mammographies Cause Breast Cancer?
Previously, the medical community did not consider the low-energy radiation used by mammograms sufficient enough to be harmful. As one study by Heyes et al. also points out, sufficient evidence exists to indicate that the risk of breast cancer because of mammography radiation has so far been vastly underestimated.2 Recent research shows that even the lower-energy X-rays provided by mammography pose a substantially greater risk of damage to the DNA. This is because the ionizing radiations used during mammograms are still at a relatively high dose, which can lead to DNA mutations that cause breast cancer.3
There is also a cumulative impact. Studies show that one mammogram can generate as much radiation as 1000 chest X-rays.4 The breast of women before menopause is highly sensitive to radiation, with one radiation exposure during mammography increasing the risk of breast cancer by about 1%. This would mean a 10% increase in the risk for each breast over a decade’s screening.5 So, despite the better technology and decreased doses of radiation, mammography poses a substantial risk.
Both age and the woman’s genetic profile increase the susceptibility to cancer after exposure to multiple mammograms.
Age: The effect of age is of particular concern. Study data show that young women who begin mammography screenings at earlier ages are actually more susceptible to the cancer-inducing effects of early and repeated exposures to mammograms. Also, the risk of breast cancer deaths induced by exposure to radiation decreases with increasing age.6
A Canadian study found a marked increase in breast cancer mortality associated with prior mammography evaluation in women younger than 50 years.7 A history of mammography before age 30 has also been associated with an increased risk of breast cancer.8
Genetic Profile: In those predisposed to cancer by family history, radiation from a mammography increases breast cancer risk. Recent genetic data indicate that women with germline mutation, which is an inherited mutation, may be especially susceptible to the cancer-inducing effects of exposures to ionizing radiation.9
Limitations Of False-Negative Results
Mammograms can also throw up “false-negative results” for younger women – a case wherein the mammogram appears normal even when the woman has breast cancer. According to a National Institutes of Health report, mammograms are unable to detect invasive cancer in one-fourth of cases among 40–49 year olds (as against one-tenth of cases among 50–59 year olds). The main reason for false-negative results is high breast density, which makes it difficult for mammograms to detect cancer. Breasts often become less dense as women age, which is why false negatives are more common in younger women. False-negative results can lead to delays in diagnosis and treatment – a serious concern when early detection is considered so critical in breast cancer therapy.10
How Many Mammographies And For Whom?
Health agencies are often divided about the impact of screening in the under-50 age group. The US Preventive Services Task Force advises against the use of routine mammography screening among women under 50, while suggesting mammography every two years in women between the ages of 50 and 74.11 The American Cancer Society, on the other hand, recommends that women aged 45–54 should get mammograms every year while women aged 55 years and over can opt for yearly or two-yearly screenings. The society states that women aged 40–44 can get annual screenings as per their discretion. But it also emphasizes that “all women should be familiar with the known benefits, limitations, and potential harms linked to breast cancer screening.”12
The onus often falls on women, especially in younger age groups, to decide for or against routine mammography screening. Screening is important, and in some cases the benefits of mammography outweigh the risks. But weigh your options carefully while considering mammography for breast cancer screening, particularly if you are below the age of 40.
Mammograms currently remain the gold standard for the early detection of breast cancer, but the silver lining is that alternatives to mammography are being researched and developed. Till then, balancing the benefits of screening with the limitations and risks is important while deciding when to start getting mammograms and how often.
References [ + ]
|1.||↑||Raftery, James, and Maria Chorozoglou. “Possible net harms of breast cancer screening: updated modelling of Forrest report.” BMJ 343 (2011): d7627.|
|2, 3.||↑||Heyes, G. J., A. J. Mill, and M. W. Charles. “Mammography—oncogenecity at low doses.” Journal of Radiological Protection 29, no. 2A (2009): A123.|
|4.||↑||Duffy, Stephen W., Laszlo Tabár, Hsiu‐Hsi Chen, Marit Holmqvist, Ming‐Fang Yen, Shahim Abdsalah, Birgitta Epstein et al. “The impact of organized mammography service screening on breast carcinoma mortality in seven Swedish counties.” Cancer 95, no. 3 (2002): 458-469.|
|5.||↑||National Research Council (US). Advisory Committee on the Biological Effects of Ionizing Radiations, and United States. Environmental Protection Agency. Radiation Office. The effects on populations of exposure to low levels of ionizing radiation: report. National Academies, 1972.|
|6.||↑||de Gonzalez, Amy Berrington, Christine D. Berg, Kala Visvanathan, and Mark Robson. “Estimated risk of radiation-induced breast cancer from mammographic screening for young BRCA mutation carriers.” Journal of the National Cancer Institute (2009).|
|7.||↑||Tarone, Robert E. “The excess of patients with advanced breast cancer in young women screened with mammography in the Canadian National Breast Screening Study.” CANCER-PHILADELPHIA- 75 (1995): 997-997.|
|8.||↑||Pijpe, Anouk, Nadine Andrieu, Douglas F. Easton, Ausrele Kesminiene, Elisabeth Cardis, Catherine Noguès, Marion Gauthier-Villars et al. “Exposure to diagnostic radiation and risk of breast cancer among carriers of BRCA1/2 mutations: retrospective cohort study (GENE-RAD-RISK).” (2012): e5660.|
|9.||↑||Andrieu, Nadine, Douglas F. Easton, Jenny Chang-Claude, Matti A. Rookus, Richard Brohet, Elisabeth Cardis, Antonis C. Antoniou et al. “Effect of chest X-rays on the risk of breast cancer among BRCA1/2 mutation carriers in the international BRCA1/2 carrier cohort study: a report from the EMBRACE, GENEPSO, GEO-HEBON, and IBCCS Collaborators’ Group.” Journal of Clinical Oncology 24, no. 21 (2006): 3361-3366.|
|10.||↑||Breast Cancer Screening for Women Ages 40-49, National Institutes of Health.|
|11.||↑||Nelson, Heidi D., Kari Tyne, Arpana Naik, Christina Bougatsos, Benjamin K. Chan, and Linda Humphrey. “Screening for breast cancer: an update for the US Preventive Services Task Force.” Annals of internal medicine 151, no. 10 (2009): 727-737.|
|12.||↑||American Cancer Society Guidelines for the Early Detection of Cancer, American Cancer Society.|