Update of staging criteria for breast cancer diagnosis recommended
New findings paint a relatively optimistic picture of women's chances of surviving a subset of breast cancers that have spread to the chest wall or skin, but not beyond.
Tumors that grow into the skin, regardless of size and whether they have involved lymph nodes, are automatically classified as stage III—and called locally advanced tumors, suggesting that they are a relatively serious form of cancer, often with poor survival. Locally advanced breast cancers of this and other types account for 5% to 10% of new breast cancer diagnoses in the United States and for 60% to 70% of cases worldwide.
Now, in the Journal of the American College of Surgeons (2014; doi:10.1016/j.jamcollsurg.2014.04.003), Fox Chase scientists in Philadelphia, Pennsylvania, cast doubt on that standard classification, by showing that women with breast cancers involving the skin have widely varied survival rates which differ by tumor size and nodal involvement.
"Many women with tumors that happen to have spread to the skin may unfortunately be given an inaccurately dire prognosis—along with, perhaps, some unnecessary treatment," says Richard J. Bleicher, MD, FACS, of Fox Chase. "We need to update our staging criteria to more accurately reflect a woman's true chances of surviving her cancer because the size of her tumor and the involvement, or lack of involvement, of lymph nodes tells us more about her prognosis than whether skin is involved."
Within the group of tumors that have spread to the skin, there is much variety, both in size and whether or not they have spread to the lymph nodes; since these tumors occur relatively rarely, however, scientists have struggled to understand how that heterogeneity might impact survival.
In this study, Bleicher and his colleagues looked at the SEER-Medicare Linked Database. They focused on patients age 65 years or older who had been diagnosed with invasive breast cancer, and had surgery to completely remove or reduce the size of their tumors.
The researchers then created two additional subgroups: those who had extensive skin involvement and those without. From there, they regrouped the cancers using the TNM Staging System, a commonly used tool for doctors to stage different types of cancer based on certain standardized criteria.
"We used this system to regroup both types of cancer by tumor size and nodal involvement," said Bleicher. "We also looked at factors like age, race, sex, histology, grade, estrogen and progesterone receptor status, surgery, chemotherapy, and radiotherapy."
After excluding some patients who lacked pertinent data and other factors, the researchers compared 924 with significant skin involvement to 66,185 others whose tumors had not spread to skin. All of the patients with significant skin involvement were originally classified as stage III. However, after restaging these tumors based strictly on the size and/or extent of the primary tumor, and whether the cancer had spread to nearby lymph nodes, nearly half (43%) were staged to earlier stages. The women restaged in this fashion did as just well as the women classified to those other stages because they didn't have skin involvement.
Based on these findings, Bleicher and his colleagues recommend adding a staging category to tumors with skin involvement, and using other criteria such as tumor size and whether or not it's spread to lymph nodes to determine stage preferentially over skin involvement. Not all of these tumors should be treated the same, he noted. "For the smallest of these lesions, they may not require such aggressive treatment as chemotherapy before surgery," he added. "We need to follow a significant number of patients in that specific category before concluding how they should best be treated."