Boost compared to no boost in breast cancer radiotherapy

Patient or population: breast‐conserving radiotherapy for breast cancer
Setting: radiotherapy centres
Intervention: boost
Comparison: no boost

Local control: recurrence at 5 years

HR 0.64
(0.55 to 0.75)

8315
(5 RCTs)

⊕⊕⊝⊝
LOW ^{1 2}

Nice did not report 5‐year local control.

Overall survival: mortality at 5 years

HR 1.04
(0.94 to 1.14)

6342
(2 RCTs)

⊕⊕⊕⊝
MODERATE ³

Disease‐free survival: disease progression/mortality at 5 years

HR 0.94
(0.87 to 1.02)

6549
(3 RCTs)

⊕⊕⊝⊝
LOW ^{4 5}

EORTC did not report 5‐year disease‐free survival.

Late toxicity, pBRA

MD 0.38 higher

(0.18 lower to 0.93 higher)

1526
(2 RCTs)

⊕⊝⊝⊝
VERY LOW ^{2 5}

Cosmesis, panel scored: fair or poor

OR 1.41
(1.07 to 1.85)

1116
(2 RCTs)

⊕⊕⊝⊝
LOW ^{1 2}

Cosmesis, physician‐scored: fair or poor

OR 1.58
(0.93 to 2.69)

592
(2 RCTs)

⊕⊝⊝⊝
VERY LOW ^{1 5 6}

Sensitivity analysis: local control ‐ recurrence at 5 years

HR 0.62
(0.52 to 0.73)

6963
(3 RCTs)

⊕⊕⊕⊕
HIGH

Subgroup analysis: local control ‐ > 40 years old, recurrence at 5 years

HR 0.65
(0.53 to 0.81)

5058
(2 RCTs)

⊕⊕⊕⊕
HIGH

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: confidence interval; HR: hazard ratio; MD: mean difference; OR: odds ratio; pBRA: percentage breast retraction assessment; RCT: randomised controlled trial

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect.
Moderate quality: We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.
Low quality: Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect.
Very low quality: We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of the effect.