Mark Lewis, MD, FASCO

Cancer killed my father and now it must prepare to die

@marklewismd Ceiling à la spider man?

ok, I’ll just levitate then

The 2026 @ASCO Plenaries might again change Standard of Care; I look forward to all these presentations! #ASCO2026 @DanaFarber_GU @DanaFarber @DanaFarber_Hale @MSKCancerCenter @UCLAHealthJCCC @sjtu1896 @OncoAlert

As we are focusing on GI Malignancies, a few things to keep in mind: 1. DPYD ✅ is now part of the FDA label for 5FU/Capecitabine 2. 🚫 5FU bolus 3. 5FU self home disconnect can help pts (check out 5FU Freedom project)! #OncTwitter @manjuggm @colontown @coloncancergal

@jenna_taglienti @drkathrynmannix You deserve all these words of support for your courage, candor, & eloquence!

@drkathrynmannix @marklewismd This is surreal. I’m still wrapping my head around it all. Incredibly grateful my message is traveling broad and wide across professions and across globe.

I wrote this in a moment I never would have chosen. A sudden pause that made me see my life clearly. The meaning of our work is profound. This experience simply helped me see more clearly what matters most. “Time is Finite” JAMA jamanetwork.com/journals/jama/…

@JPolydoris What tea!

@marklewismd Want me to tell you abt guy who ditched me for a middle aged retired librarian type who out right catfished him on X from three states away?

Knowing someone on socials means you’ve heard their hit singles But friendship IRL is listening to the whole album, no skips

(Plus the live debut of some new stuff that might take some getting used to ;)

@Rea_Booker Oncology GOALS :)

@marklewismd Amazing!! Congrats! 🎉🥳 I have her beautiful apoptosis drawing up in my office at our cancer centre!

Since many of you have supported my daughter’s paintings when I’ve shared them on here, I’m delighted to report that she just won a statewide award among Utah high school students for her excellence in the visual arts I am one proud papa! deseret.com/utah/2026/04/1…

Fibroblasts:

@UDarnTuten TIL …

@marklewismd Ok, I’m going to have to insert my useless knowledge of Southern history. It’s actually common to cut off a raccoon penis. Some CW reenactors have them in the brim of their cap, I’ve heard them called “Dixie whistles”

Normally you have to consult ID to get this level of detail about zoonotic exposure

@nursekristinrn I obviously have no objectivity when it comes to my own child but I’m amazed at how the two halves of her brain connect — thank you for your kind, insightful feedback 🙏

@marklewismd Beyond her amazing art I am moved that she "gets" biology and physiology at such an exceptional level. Kudos 👏

My daughter’s depiction of the bronchial tree

@Factsonlygurl She’s 18 and a senior in high school

@marklewismd her age-ish...not to pry, but my daughter is an artist and I wanted to extend some encouragement for some things that helped her along the way.

See one Uh, on second thought, maybe don’t do one

@ultra_kidney Wishing you the best of health!

@marklewismd this is gorgeous. I am currently navigating the unknown pathway towards non-directed living lobar lung donation with the ethics committees at Duke. Your tweet is some synchronistic timing. 🫡

@brunolarvol @rcarvalhoonco “Generally tolerable”? “Favorable risk/benefit”? Also important to specify if AEs are reversible, I think 🤷🏻‍♂️

@marklewismd @rcarvalhoonco What language should be used to describe toxicity? Would a quantitative score help ? (Working on this )

You can be bullish on daraxonrasib, as I am, and still avoid minimizing side effects like this as “manageable toxicity” We don’t truly understand the visceral experience of taking a medication like our patients do — let’s allow them to be the arbiters of what’s manageable or not