The size and extent of cancer at the time of detection are among the most important factors in determining a breast cancer patient’s prognosis.[3] Breast cancers that are discovered through the presence of symptoms are generally larger and have more likely spread beyond the breast prior to detection than cancers found through breast cancer screening. Mammography screening has proven to be effective in finding cancers at earlier stages.[4] This alone could account for improved outcomes of women who are diagnosed with cancer through mammography. However, the Journal of the American Medical Association reports that women with tumors found through mammography screening tend to have better outcomes even than women with similarly-sized tumors that were found in other ways.[5]
Over the past 30 years, the U.S. has seen an increase in the diagnosis of stage 0, or ductal in situ carcinoma (DCIS) and very early stage (stage I) breast cancer, while diagnosis of more advanced-stage breast cancers have either dropped or remained steady. In fact, diagnosis of DCIS has increased over 300% in women over 50, suggesting that higher rates of screening and better screening technology have allowed health care provider to detect cancer at earlier stages.[6]
The prognosis for a woman who receives early diagnosis of breast cancer is much better than for one diagnosed at a later stage. The National Breast Cancer Foundation reports that women diagnosed with stage 1 cancer see a 5-year survival rate of 98%.[7] Susan G. Komen reports relative 5-year survival rates of 99% in women diagnosed with localized breast cancer, 84% in those with regionalized cancer (cancer that is contained within the organ in which it began), and 24% in women whose cancer cells have spread to other parts of the body. These data illustrate the critical importance in detecting cancer as early as possible.
Those whose breast cancer is diagnosed early also tend to receive much less invasive and less debilitating treatments than later-stage patients. According to a study by the American Cancer Society, 30% of women diagnosed in 2008 with stage I or II breast cancer underwent only breast-conserving surgery (BCS) and radiation therapy (RT), and 10% received BCS alone. Among women diagnosed with stage III or IV cancer, 31% underwent mastectomy, RT, and chemotherapy. Only 2% had BCS alone.
Because so many women are affected by breast cancer at some point in their lives, and because early detection can greatly improve outcomes for these women, Iowa Radiology supports the recommendations of the American Medical Association, the American College of Obstetricians and Gynecologists, the American College of Radiology, the American Cancer Society, the American College of Family Physicians, and the National Cancer Institute advising annual mammograms for women beginning at age 40.
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Sources
[1] http://www.cancer.org/cancer/breastcancer/detailedguide/breast-cancer-key-statistics
[2] http://ww5.komen.org/BreastCancer/UnderstandingRisk.html
[3] http://www.cancer.org/cancer/breastcancer/moreinformation/breastcancerearlydetection/breast-cancer-early-detection-importance-of-finding-early
[4] http://www.who.int/cancer/detection/breastcancer/en/
[5] JAMA. 2004 Sep 1. 292(9).1064-73.
[6] http://ww5.komen.org/BreastCancer/DistributionOfCancerStagesPopulation.html
[7] http://www.nationalbreastcancer.org/breast-cancer-stage-0-and-stage-1