Cancer recurrence is more likely to happen in women who are younger or who have tumors that are either invasive or are of a triple-negative subtype, the group found. Still, women whose cancers are detected on breast ultrasound have a five-year overall survival rate of 100% and a recurrence-free survival rate of 98% -- numbers that cement ultrasound's place in the arsenal of breast cancer screening tools, according to the study authors.
"We were surprised that the study had such excellent outcomes," contributing author Dr. Woo Kyung Moon of Seoul National University Hospital told AuntMinnie.com. "[Especially since] for breast cancer detected at screening mammography, overall survival and recurrence-free survival rates in Korean women are about 96% and 92%, respectively."
Supplemental screening modalities such as digital breast tomosynthesis (DBT) and MRI have been used to improve early detection of breast cancer in women who have dense tissue and negative findings on mammography. Ultrasound has been used for this as well, and it has the advantage of not imparting radiation and being well-tolerated by patients, lead author Dr. Soo-Yeon Kim and colleagues wrote (Radiology, August 2017, Vol. 284:2, pp. 354-364).
Dr. Woo Kyung Moon of Seoul National University Hospital.
But little research has been published on the factors associated with recurrence of cancer in women whose tumors were detected on breast ultrasound, or even on their survival rates.
To shed light on the topic, the researchers commenced a study that included 501 women with breast cancer identified with breast screening ultrasound between January 2004 and March 2011. Of these patients, 15.8% had high-risk factors for breast cancer. Of 501 identified cancers, 425 were invasive (84.8%); most were node-negative (90.8%) and low or intermediate grade (82.6%).
All patients underwent surgery, with 89% having a less aggressive breast conservation procedure. Of the cohort, 42.6% of patients with invasive cancers received adjuvant chemotherapy. The researchers defined overall survival from the date of breast cancer diagnosis to that of death, the last confirmation of the patient being alive, or the most recent follow-up; recurrence was confirmed with biopsy or PET/CT.
Kim's team found that women whose cancers were detected on breast ultrasound had a five-year overall survival rate of 100% and a five-year recurrence-free survival rate of 98%. At median follow-up of seven years, there were 15 recurrences, five of which were in the ipsilateral breast and 10 of which were in the contralateral breast. No distant metastases or deaths were noted within the follow-up period.
What were the characteristics of the women who experienced cancer recurrence? The team identified a number of factors. These included having invasive cancer, being younger than 40, having a triple-negative tumor subtype, and having lesions classified as BI-RADS 4A, a suspicious finding that has a low suspicion of being cancer -- in fact, 69% of lesions in this category were recurrent tumors.
In patients with invasive cancer detected on screening breast ultrasound, the researchers found the following factors predicted recurrence:
|Factors associated with recurrence in ultrasound-detected invasive cancer
|40 and younger
|40 and older
|HR-, HER2- (triple negative)
|4B, 4C, and 5
Awareness of these recurrence factors can help physicians and patients make better decisions about supplemental screening, according to the study authors.
"This information can be used to help inform patient and clinician decision-making regarding the use of supplementary screening in women with dense breasts and the selection of appropriate treatment in women with breast cancers detected at screening ultrasound," they wrote.
The study demonstrates that women with breast cancers detected at screening ultrasound have excellent prognoses. It also points to the benefit of early breast cancer detection using supplemental modalities, especially for those women who may be more vulnerable to recurrence, Kim and colleagues noted.
"The occurrence of these favorable outcomes even in the context of less aggressive surgery and less toxic treatments reflects the importance of early breast cancer detection with supplemental screening," the group concluded.
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