I'm not @Jonathan, but I would've LOVED to have written a breast cancer storyline for Erica/Susan Lucci.
Mona had battled cancer years before; and as we all know, having a history of cancer in your family places you at a greater risk of developing cancer as well. Also, Erica was the ideal character to tell that story as far as what you SHOULDN'T do when you suspect you might be ill: ignoring the telltale signs, preoccupying yourself with work and with other matters, hoping it'll just "go away."
I wanted to explore each and every beat with Erica: from her finding the lump in her breast, to her immediate denial that it is anything serious and concentrating instead on some major project happening at Enchantment (something that would've involved Bianca and Kendall, of course), to being forced to confront the issue (by none other than Brooke English!) and undergo a biopsy, to Erica's worst fears being confirmed (and being tempted in the moment to self-medicate with pills or alcohol), to her fears over how the cancer and course of treatment might affect her beauty (and the admission that, for all of her life, she has taken her beauty for granted to the point where she isn't sure whether she could BE anything else), to major milestones, such as undergoing the mastectomy, beginning chemo/radiation treatments, losing her hair, etc.; to receiving a cancer-free diagnosis; to her attempts at getting her life and career back on-track as a cancer survivor; to learning that, in fact, the cancer has returned (and perhaps spreaded to some other area, such as her lungs); to her vowing once more to beat it (even as she fears privately that she might not); to her actually beating it a second time (and hopefully, this time, for good).
And with her every step of the way (aside from her loved ones, of course) would be Brooke, of all people, as the two longtime nemeses would develop a bond of sorts, as Brooke would end up helping Erica through what might be her biggest crisis yet (with one consequence being Opal, as Erica's sole female friend up to that point, feeling jealous and resentful for awhile). One scene, in particular - where Erica accuses Brooke of not understanding what it means to feel alone and scared, and Brooke admits (publicly, for the first time, I think) how she had to undergo an abortion after getting raped by Eddie Dorrance - would be pivotal in Brooke and Erica reaching a new understanding with each other.
More than all that, however, and because I've always adhered to Agnes Nixon's belief that storytelling should entertain AND educate, Erica's breast cancer battles would provide the impetus for a new romantic relationship with the doctor assigned to her case - ideally, he would've been played by Robert Urich - and maybe the first man in recorded history NOT to fall immediately for Erica's considerable charms. In fact, he might be the first man ever to admit that he can't stand her! So, of course, you know it's only going to end in romance, lol.
Jack would be nibbling around, of course, once again playing the rival for her affections. He even goes so far as to buy Erica another engagement ring. Then, he witnesses a moment between Erica and the doctor - not a kiss or a passionate embrace, but something.
Later, Erica finds the ring and accepts Jack's proposal before he's even actually proposed! However, Jack tells Erica what has been apparent to many except her: that she's actually in love with her doctor...and he's just as crazy about her. Although Erica insists that there is nothing in common between her and her doctor and that she is as committed as ever to reuniting with Jack, he, on the other hand, tells her he'll always be there for her, and they part as friends.
In a way, that ties in with my post-cancer plans for Erica. Specifically, she starts The Mona Foundation. Named in honor of her late mother - herself, a cancer survivor - it would've been a non-profit organization, promoting cancer awareness for women, and older woman in particular.