Of 1,017 physicians invited to participate, 232 (22%) accessed the Web-based survey within 6 weeks. Fourteen were either not medical oncologists or had not ordered the 21-gene RS assay for any patient with N+/ER+ disease. Fifty-eight did not complete the survey, leaving 160 (16%) completed surveys. Most of the oncologists classified their practices as community-based (71%), followed by academic (25%) and other (4%) settings. They were equally dispersed throughout the four major geographic regions of the United States and had a median of 11 years (range, 1-45 years) of practice experience. On the basis of their selection of the one statement that they believed best fit their rate of new technology adoption, our participating oncologists were categorized as 12% first anywhere, 24% first locally, 53% sooner than most locally, 11% later than most locally, and 1% last locally (). Of the 160 respondents, 112 (70%) reported being mostly or completely satisfied with the data supporting the use of the 21-gene RS assay in postmenopausal patients with N+/ER+ disease, and 75 (47%) reported the same level of satisfaction with the data regarding its use in premenopausal patients with N+/ER+ disease. One hundred twenty respondents (75%) predicted a moderate or significant increase their use of the assay in N+/ER+ patients if it were included in ASCO guidelines, and 123 (77%) predicted an increase in assay use if it were included in NCCN guidelines (Appendix Fig A1, online only).
Characteristics of Medical Oncologists Who Ordered the 21-Gene RS Assay for Patients With N+/ER+ Breast Cancer
In the 3 months before completing the survey, oncologists ordered the assay for a mean of 1.9 N+/ER+ patients (median, 1; range, 0-20) and 9.5 N−/ER+ patients (median, 6; range, 0 to 75). Most respondents (91%) did not have an upper age limit for ordering the assay. Eighty-three percent reported that they did not have a lower age limit; 9% reported limiting its use to postmenopausal women only. Reasons for ordering the assay given by most or all respondents were as follows: to obtain additional data to help predict the benefit from chemotherapy (71%); to obtain additional data to help predict the patient's recurrence risk (59%); to provide reassurance regarding prognosis or treatment (41%); and to confirm pathology report results regarding ER, progesterone receptor, or human epidermal growth factor receptor 2 status (14%; Appendix Fig A2, online only). In most cases (67%), the patient contributed to the decision to order the 21-gene RS assay. The patient's reluctance to receive chemotherapy was most commonly cited as the most important factor in the oncologist's decision to order the assay (47%), followed by presence of comorbid conditions that increased risks of toxicity associated with adjuvant chemotherapy (19%), absence of medical conditions that significantly impaired quality of life or limited life expectancy (10%), advanced age of the patient (9%), a recommendation by a colleague or expert (2%), and other factors (14%).
The median age of respondents' last patient with N+/ER+ disease for whom the 21-gene assay was ordered was 61 years (range, 34-82 years), and 79% of patients were postmenopausal. T1, T2, or T3 disease was reported in 62%, 35%, and 3% of patients, respectively (unknown in 1 patient). One, two, three, or four or more positive nodes were reported in 69%, 18%, 6%, and 3% of patients, respectively (unknown in eight patients; ). The 21-gene RS assay classified 87 (54%) patients as having a low RS, 60 (38%) as having an intermediate RS, and 13 (8%) as having a high RS. Oncologists' postassay risk assessments (low, intermediate, high) agreed with the assay results for 89% of patients.
Characteristics of Patients With N+/ER+ Breast Cancer
For 138 patients, oncologists indicated that they made treatment recommendations before ordering the assay. Among N+/ER+ patients who had a preassay treatment recommendation, 72 (52%) were found to have a low RS, 53 (38%) an intermediate RS, and 13 (9%) a high RS (). After obtaining the RS, oncologists indicated that they changed their treatment recommendation in 70 patients (51%). These changes were seen for patients with RSs in every risk category: 43 (60%) with a low RS, 20 (38%) with an intermediate RS, and seven (54%) with a high RS. The recommended treatment decreased in intensity from chemotherapy plus hormonal therapy to hormonal therapy alone in 46 patients (33%). Among the 72 patients with a low RS, chemotherapy was eliminated in 35 (49%); among the 53 patients with an intermediate RS, chemotherapy was eliminated in 11 (21%); and among the 13 patients with a high RS, chemotherapy was not eliminated for any patient. Overall, the recommended treatment intensity increased from hormonal therapy alone to chemotherapy plus hormonal therapy in 13 patients (9%): four (6%) with a low RS, six (11%) with an intermediate RS, and three (23%) with a high RS. In 11 patients (8%), treatment changes did not fit our definitions of either increased or decreased intensity (eg, changes in chemotherapy components only or changes from hormonal therapy alone to chemotherapy alone; ).
Effect of the 21-Gene RS Assay on Treatment Recommendations for Patients With N+/ER+ Breast Cancer