Seeking healing through Surah Rahman?

Assalamu alaikum dear brothers and sisters, A while back, I shared that my mother, Sadia, is fighting stage 4 cancer. I want to thank everyone who kept her in their prayers-may Allah reward you all abundantly. If you missed my earlier post, I humbly ask you again to please make dua for her healing. Now, someone advised me to play Surah Rahman recited by Qari Abdul Basit for her, exactly three times a day for seven days-no more, no less. Does anyone know if there's any basis or evidence for this practice? I would be truly grateful for any recommended duas, surahs, Quranic healing methods, or hadith that could help my mother overcome this illness. Jazakum Allahu khairan.