“…the long-term effects of radiation therapy,which increases a woman’s risk for lung cancer and heart disease.” 
Chris did not footnote this particular statement therefore failing to substantiate his claim with science. It’s basic fear-mongering based on old tropes.
But there’s great news!
Body position while going through breast cancer radiation treatment matters says The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute. Nearly all women used to undergo breast radiation therapy lying on their back in what is called a supine position. There was a slight chance that radiation can damage healthy lung and heart tissue in that supine position but it took science-based medical research to find an even better way. Recent studies show that a new approach of being in a prone position during radiation therapy reduces the amount of lung and heart tissue affected by radiation therapy by 90 percent!  It’s well worth reading the article about this in the link below.
As for that fear-mongering about radiation therapy..
In a study published online in CANCER, a peer-reviewed journal of the American Cancer Society, most patients agreed that their initial negative impressions about radiation were unfounded. The study revealed that 93 percent of breast conservation patients and 81 percent of mastectomy patients agreed with the statement, “If future patients knew the real truth about radiation therapy, they would be less scared about treatment.” 
 Chris Wark, ‘Chris Beat Cancer” book, page 45