# Drugs before or after the operation

Source: https://onco.cc/terms/neoadjuvant-versus-adjuvant-breast/  
OnCo record `neoadjuvant-versus-adjuvant-breast` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Giving the same drugs before surgery rather than after does not change how long a woman lives, but it shrinks the tumour so that more women keep their breast, and it shows whether the drugs worked, which now decides what treatment comes next.

## Summary

The survival question was answered by the Early Breast Cancer Trialists' Collaborative Group, pooling individual data for 4,756 women in ten randomised trials that compared the same chemotherapy given before or after surgery. More than two thirds of women given chemotherapy first had a complete or partial clinical response, and breast-conserving therapy was performed in 65 percent of them against 49 percent of those treated after surgery. There was no significant difference in distant recurrence at fifteen years (38.2 against 38.0 percent), breast cancer mortality (34.4 against 33.7 percent) or death from any cause (40.9 against 41.2 percent).

There is a cost, and it is local. Fifteen-year local recurrence was 21.4 percent after chemotherapy given first against 15.9 percent after surgery first, an absolute increase of 5.5 percent (rate ratio 1.37, 1.17 to 1.61, p=0.0001). The overview's explanation is that a tumour shrunk by chemotherapy may recur more often after conservation than a tumour of the same measured size that was never shrunk, and its recommendation is careful tumour localisation, detailed pathological assessment and appropriate radiotherapy rather than a retreat from the strategy.

What has changed since those trials is the second reason to treat first, which they were not designed to measure: the response itself is information. Whether cancer remains in the breast and nodes at surgery now decides what is given afterwards, and that decision differs by receptor subtype, so it belongs on the subtype pages rather than here. The axillary and radiotherapy consequences are shared and are covered here: targeted axillary dissection for staging the axilla afterwards, ACOSOG Z1071 for why marking the node is necessary, and NSABP B-51, which found that regional nodal irradiation adds nothing once the nodes are pathologically clear.

In England NICE NG101 recommendations 1.13.25 to 1.13.29 govern radiotherapy after chemotherapy given first, and they key the decision to both the pretreatment stage and the post-treatment pathology.

## Fields

- Kind: Term
- Last checked: 2026-09-25
- Also known as: neoadjuvant versus adjuvant breast cancer; primary systemic therapy; preoperative chemotherapy in breast cancer

## Sources

- EBCTCG: chemotherapy before or after surgery, 4,756 women in ten trials (Lancet Oncology 2018): https://doi.org/10.1016/S1470-2045(17)30777-5
- NICE NG101 recommendations 1.13.25 to 1.13.29, radiotherapy after neoadjuvant chemotherapy: https://www.nice.org.uk/guidance/ng101

## Connected records

- terms: [Breast conservation or mastectomy](https://onco.cc/terms/breast-conserving-surgery-versus-mastectomy/), [Neoadjuvant / adjuvant / perioperative](https://onco.cc/terms/neoadjuvant-adjuvant/), [Pathologic complete response (pCR)](https://onco.cc/terms/pcr/), [Residual cancer burden (RCB)](https://onco.cc/terms/rcb/), [Targeted axillary dissection](https://onco.cc/terms/targeted-axillary-dissection/)
- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/), [Surgery & Interventional](https://onco.cc/fronts/surgery/)
- trials: [ACOSOG Z1071 (Alliance)](https://onco.cc/trials/acosog-z1071/), [ATNEC](https://onco.cc/trials/atnec/), [NSABP B-51 / RTOG 1304](https://onco.cc/trials/nsabp-b51/), [Targeted axillary dissection (MD Anderson prospective study)](https://onco.cc/trials/targeted-axillary-dissection-md-anderson/)

---
JSON: https://onco.cc/api/v1/entities/neoadjuvant-versus-adjuvant-breast.json