Higher Oncotype DX Scores Tied to Persistent Use of Endocrine Treatment in Breast Cancer

Patients with higher Oncotype DX scores are more likely to complete the recommended 5 years of endocrine therapy.

Despite the established benefit of endocrine therapy in local and distant breast cancer recurrence, many patients with low-risk, estrogen receptor (ER)-positive breast cancer will discontinue therapy prior to 5 years. Findings from a retrospective review evaluating Oncotype DX test results showed that patients with higher Oncotype DX scores are more likely to complete the recommended 5 years of endocrine therapy. Jonathan Pirruccello, MD, lead author on the poster, presented results during the 2021 San Antonio Breast Cancer Symposium.1

“Our findings suggest that the Oncotype DX breast recurrence score may influence [a patient’s] persistence [in taking] endocrine therapy,” Pirruccello, a resident at Dartmouth-Hitchcock medical center in Lebanon, New Hampshire, said during the presentation of data.

The investigators hypothesized that patients with higher Oncotype DX breast recurrent scores may have higher rates of persistence when compared to a similar cohort with lower recurrence scores. Further, the individual perception of risk of recurrence conveyed by the Oncotype DX breast recurrent score directly influences persistence with endocrine therapy. Non-persistence to endocrine therapy represents a major unmet need in breast cancer care with about 1 in 3 women discontinuing endocrine therapy early.2

The study evaluated 194 patients with low-risk, ER-positive breast cancer for at least 5 years. An Oncotype DX score of less than 26 was defined as low risk.

Persistence was determined by chart review and defined as a minimum duration of 55 months on endocrine therapy. The average recurrence score was 15.2 in the persistent group (n = 145) compared with 13.7 in the non-persistent group (n = 49; P = .086) and the rate of distance and local recurrence was determined for both groups. The investigators reported that the average recurrence risk was 10.1% in the persistent group and 9.2% in the non-persistent group (P = .091). The recurrence rate for distant and contralateral/local disease was 2% in the persistent group and 18% in the non-persistent group. When observing only the distant recurrent rate, the persistent group had a recurrent rate of 0.6% compared with 10% in the non-persistent group. Recurrence rates were also lower for contralateral/local disease in the persistent group (1.3%) vs the non-persistent group (8%).

Metastatic disease recurrence in women with low-risk, ER-positive breast cancer is due primarily to non-persistence with endocrine therapy, according to investigators. There were 6 cases of metastatic breast cancer recurrence in a 5-to-8-year follow-up period, with 84% (5 of 6) of distant recurrences reported in the non-persistent group, according to investigators.

“This finding further substantiates the overall effectiveness of endocrine therapy in reducing the risk of future recurrence in patients with low-risk, ER-positive breast cancer,” Pirruccello said. The findings suggest that the majority of early metastatic recurrences in women with low-risk breast cancer may occur due to failure to complete the recommended the 5-year course of therapy.

“Mindful framing of Oncotype DX test results by clinicians represents a potential avenue to increase persistence through the modulation of individual risk perception,” said Pirruccello. “This may ultimately lead to decreased rates of disease recurrence in patients with low-risk, ER-positive disease, including a decrease in local and distant disease recurrence,” he continued.

The investigators recommended additional data collection to complete a total of 10-years follow up to determine a recurrence rate that follows literature standards. They further recommended that any future interventions aimed at improving persistence should consider the effect of risk perception, particularly for those with lower Oncotype DX scores.

Oncotype DX is an assay that uses a 21 gene panel to estimate 10-year risk of recurrence in patients with ER-positive breast cancer who are undergoing endocrine therapy. The assay generates a recurrence score for each tumor sample, based on expression levels of 16 breast cancer-related genes normalized to 5 reference genes.3 An important risk factor for recurrence is non-persistence or early discontinuation of endocrine therapy.

1.Pirruccello J, Kuhn E, Boothe JT, Chamberlin MD. The influence of the oncotype DX breast recurrence score on persistence to endocrine therapy in patients with low-risk ER/PR+ invasive breast cancer. resented at: 2021 San Antonio Breast Cancer Symposium; December 7-10, 2021; Virtual. Abstract P1-13-06.
2.Murphy CC, Bartholomew LK, Carpentier MY, Bluethmann SM, Vernon SW. Adherence to adjuvant hormonal therapy among breast cancer survivors in clinical practice: a systematic review. Breast Cancer Res Treat. 2012;134(2):459-478. doi:10.1007/s10549-012-2114-5
3.Oncotype IQ. About the Oncotype DX breast recurrence score test. Accessed December 8, 2021. https://bit.ly/3IzfgP1.