I wore the Target post op front opening bra during radiotherapy- no wires and soft cotton so not irritating and could absorb the creaming from calendula and Dermaveen .I have now post radiotherapy changed to an aah bra and truly first time I have been comfortable since lumpectomy last March but mine are a nylon mix so would not recommend during radiotherapy and until after your skin heals.My daughter buys Target sports bras which are sim8lar but cotton.One small tip raglan sleeve top helped as well as a soft fabric - I reckon in the heat a men’s bonds undershirt might be an idea