ESTRO Multidisciplinary Management of Breast Cancer 2017

Validity of Estimates of Effect of Treatment on Recurrence Rates

• Valid estimates of the causal effect of radiotherapy on recurrence rates can only be made in terms of any recurrence.

• Valid estimates of the effect of radiotherapy on local recurrence rates cannot be made – although many papers claiming to do so have been published • Valid estimates of the effect of radiotherapy on distant recurrence rates can be made – but only if information on distant recurrences occurring after any earlier local recurrence are available, and these will be affected by the treatment given for the local recurrence as well as the initial radiotherapy

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