BS22 PROGNOSTIC INDEX IN SCREEN‐DETECTED BREAST CANCER

Abstract

A meta‐analysis of symptomatic breast cancer trials advises chemotherapy to women less than 70 years of age at high risk of death (i.e. benefit of >1% survival from treatment). UK screen detected breast cancers (SDBC) (aged 50–65 years) have an overall 95.5%, 5 year relative survival, a figure similar to the Two Counties Swedish Trial survival. NIH Guidelines (2001) recommend chemotherapy for all cancers greater than 10 mm in size (i.e. 35% of screen detected breast cancers) yet the overall benefit for chemotherapy is based on mortality data from symptomatic cancer trials and in postmenopausal women aged greater than 50 years of age the average benefit is a 10% reduction in mortality (EBCTG Overview).We have compared screen detected breast cancer SDBC with symptomatic breast cancer in the same age group (50–65 years) with regard to clinicopathological features, recurrence and survival in one unit from 1990–1998 and validated a new index on 4,195 operable screen detected breast cancer SDBC treated by NHSBSP surgeons from 1996–1997 in the United Kingdom. Median follow‐up on 1,607 breast cancers was 70 months (range 21–103) and indicated that breast cancer diagnosis by screening (as opposed to symptomatic presentation) had a reduced risk of recurrence RR = 0.37, 95% CI 0.23–0.53 and fatality RR = 0.28, (0.19–0.42), which was independent of grade, node status and tumour size. Smaller tumours and higher node negativity occurred in SDBC’s but tumour grade and oestrogen receptor status did not differ from symptomatic cancers. A screening prognostic index (MSI) based on combining scores for grade (1; 2 or 3), size less than 15 mm = 1, 1.5–2.5 = 2, greater than 2.5 = 3) and nodal status (negative = 1, less than 4 nodes = 2, greater than 4 nodes = 3) was defined in the initial series and demonstrated that those with scores 3–5 had a 99.5% survival at 5 years in the screening group with a 98.6% survival for score 6. For SDBC scores 7–9 overall survival at 5 years dropped to 80%. In a larger screen detected breast cancer from the BASO Audit overall survival is shown below: Manchester SI All Cases 1996–97 Grade III 1996/97 Cases Only Chemotherapy Use in 2001/2 N % Node Positive 5 Year Relative Survival (±95% CIs) 3 833 (20) 0% 0% 100% 1% 4 1111 (26) 0% 9% 98.5% (97.1–100.0) 6% 5 1090 (26) 20% 25% 96.3% (94.7–98) 22% 6 630 (15) 42% 55% 93.6% (91–96.1) 49% 7 363 (9) 49% 80% 81.1% (78.5–85.7) 63% 8 143 (3) 66% 100% 71.6% (63.4–79.8) 83% 9 26 (1) 100% 100% 57.1% (38–78–3)† 85% Chi‐Squared test for trend (†p < 0.001) Index scores identified women at high risk of mortality (score 7–9). Patients in the original series in Manchester with SDBC received significantly less adjuvant radiotherapy and chemotherapy than symptomatic cancers yet had a better overall survival. Only 1.9% of screen detected breast cancer scores 3–5 received chemotherapy compared to 7% of symptomatic cancers whilst in scores 7–9, 81% in both groups received chemotherapy. This data indicates that despite the NIH Guidelines screen detected breast cancer needs less chemotherapy than symptomatic cancer and has a good overall survival. The better survival of mammographically detected breast cancer (age 50–70 years) suggests that women whose cancer is diagnosed by mammography will receive unnecessary adjuvant chemotherapy if symptomatic guidelines are applied. The new Manchester Screening Index identifies only 13% of postmenopausal SDBC women with a 5 year survival below 93.6% who would benefit from chemotherapy (scores 7–9).