Spot-scanning proton therapy for targets with adjacent cardiac implantable electronic devices – Strategies for breast and head & neck cancer

•Secondary neutron dose was calculated for pacemakers and implantable cardioverter defibrillators for patients with breast and head & neck cancer.•Decision algorithms for selecting patients with targets adjacent to pacemakers and implantable cardioverter defibrillators for proton therapy were established.•Eligibility for proton therapy depends on individual evaluation for some patients.•The expected gain from proton therapy should outweigh the risk of device malfunction.