Yep. Turns out you're right. Brachytherapy did the trick for him. Sorry to take so long to reply back, but it took me this long to confirm that, yep, you're right.
Thanks for the corrective surgery (instruction). :-)
. . . the doctors said they thought campaigning was perfectly within his physical capabilities and, if he started treatment right way, he would have recovered and been "full speed" by the time the campaign normally kicked in. He delayed that procedure until September and went about his mayoral duties as usual.
So, why do you attribute his withdrawal to spinelessness? I just don't see it.
Two reasons for his withdrawal, IMO. 1) He wasn't gaining any steam against Hillary and 2) his affair with Judy had just been exposed by the media, followed by a press conference where he announced he was going to seek a divorce (the first his wife heard about it). Then he tried to kick his wife out of Gracie Mansion which didn't go over too well. Soon after, he announced the cancer and the media backed off, somewhat, but his numbers continued to fall. Bottom line (IMO): he knew he would lose against Hillary if he continued.
I said "spineless" because he weasled out of the race at the 48th hour, leaving the GOP high and dry. I can think of lots of other words to describe his behavior, all of which point to a narcissistic man of low character, seeking power, who hit the road when the going got tough.