[GS5-00] Long-term influence of estrogen plus progestin and estrogen alone use on breast cancer incidence: The Women's Health Initiative randomized trials

Chlebowski RT, Anderson GL, Aragaki AK, Manson JE, et al.

The authors conclude that: xxxx CEE-alone and CEE plus MPA use have opposite effects on breast cancer incidence. CEE alone significantly decreases breast cancer incidence which is long term and persists over a decade after discontinuing use. CEE plus MPA use significantly increases breast cancer incidence which is long term and persists over a decade after discontinuing use. As a result of the attenuation of subgroup interactions: all postmenopausal women with prior hysterectomy using CEE-alone have the potential benefit of experiencing a reduction in breast cancer incidence while all postmenopausal women using CEE plus MPA have the potential risk of experiencing an increase in breast cancer incidence.

Yau C, van der Noordaa M, Wei J, Osdoit M, et al.

The authors conclude that: xxxxLong-term prognosis after pCR was similarly excellent in all phenotypic subtypes. RCB index and classification was independently and strongly prognostic in all subtypes, and generalizable to multiple practice settings. Prognostic differences by RCB class occurred within 5 years in HR- BC, but extended to 10 years in HR+ BC. RCB-I had slightly worse EFS than pCR in HR- BC and HR+/HER2+ BC (after 5 years), but the same EFS as pCR in HR+/HER2- BC. Complete analysis of all subjects, including neoadjuvant treatments, will be presented at the meeting.

[GS5-02] Detection of circulating tumor DNA (ctDNA) after neoadjuvant chemotherapy is significantly associated with disease recurrence in early-stage triple-negative breast cancer (TNBC): Preplanned correlative results from clinical trial BRE12-158 

Radovich M, Jiang G, Chitambar C, Nanda R, et al.

The authors conclude that: Detection of ctDNA in early-stage TNBC after neoadjuvant chemotherapy is an independent predictor of disease recurrence, and represents an important novel stratification factor for future post-neoadjuvant trials.

[GS5-03] Diagnosing residual disease and pathologic complete response after neoadjuvantchemotherapy in breast cancer patients by image-guided vacuum-assisted breast biopsy:results of a prospective multicenter trial

Heil J, Pfob A, Sinn H, Rauch G, et al. 

The authors conclude that: The i.g.VAB alone did not reach the anticipated diagnostic accuracy in this study. However, combining the results of i.g.VAB and breast imaging after neoadjuvant chemotherapy detects residual disease in women with breast cancer with a FNR <10%. This finding will guide ongoing and future trials aiming for tailoring, de-escalating, and potentially avoiding unnecessary surgery in women without residual disease after neoadjuvant chemotherapy.

Tasoulis M, Lee H, Yang W, Pope R, et al.

The authors conclude that: This large pooled multicenter data suggests that a standardized protocol using image-guided VAB of a tumor bed measuring up to 2 cm with at least 6 samples allows reliable prediction of residual disease and pCR. These results should inform the design of de-escalation trials in NAC exceptional responders testing the safety of eliminating surgery.

Basik M, Cecchini RS, De Los Santos JF, Umphrey HR, et al.

The authors conclude that: In the current findings of NRG-BR005, bx did not achieve an NPV of >90% and identified only 50% of the pts who had residual disease at surgery following NCT. The findings do not support breast-conserving treatment without surgery based on the study criteria for cCR and rCR/near rCR and negative tumor bed bx. Further analyses including central review of the tri-modality imaging and assessment of the imaging algorithm with and without the addition of bx are underway. Once these analyses are combined with information on biologic subtypes, a new prediction model may be defined.

[GS5-06] Toward omitting breast surgery in patients with a pathologic complete response after neoadjuvant  systemic treatment: interim analysis of the MICRA trial (Minimally Invasive Complete Response Assessment)

Vrancken Peeters MTFD, van Loevezijn A, van der Noordaa MEM, van Duijnhoven FH, et al.

The authors conclude that: Ultrasound-guided core biopsies of the breast in patients with excellent response on MRI after NST are not accurate enough to safely select patients with pCR for omission of surgery.

GS5-07. Discussant
Kalliopi Siziopikou, MD, PhD
Northwestern University
Chicago, IL