We are fortunate that Mass General has recently published an excellent paper on this topic that helps give guidance (Naoum et al., PMID 37967296). As expected, axillary soft tissue involvement is a high-risk feature, and these patients are at high risk for metastatic disease. For example, if there is LN involvement, axillary soft tissue involvement, and extracapsular extension, the 10-year distant metastasis incidence would be 42%. If it's only LN and axillary soft tissue involvement, these pati...
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There is no specific guideline for this. But, as we do for patients who occasionally miss fulvestrant doses, I would try to schedule the next dose as soon as possible. Another option would be to consider an alternative endocrine therapy option such as AI, tamoxifen, which do not require for patients to come to the clinic every month, depending on the clinical situation.