YEAR IN REVIEW: Mark is diagnosed with lymphoma and spends much of the year receiving treatment recuperating. Blink-182, likewise, remains sidelined by those circumstances and the ongoing coronavirus pandemic.

4/20/2021: Mark gets an appointment to his primary care physician for an undiagnosed pain in his shoulder.

6/23/2021: Mark inadvertently shares a photo to his Instagram Story meant for close friends, revealing he was diagnosed with cancer and is receiving treatment.

9/30/2021: Mark tells fans he is cancer-free.

12/2/2021: GQ runs a profile on Mark, his cancer diagnosis, and the future. The column reveals that Tom, Mark, and Travis had recently met up for a meeting at Mark's home.