Charity cyclist Jane Tomlinson tackled the highest mountain pass of her life on Sunday during her 4,200-mile Ride Across America.
Jane has raised over £1.25m for charity since diagnosis in 2000
The mother-of-three, who was told she had terminal cancer six years ago, climbed the 11,312ft (3,448m) Monarch Pass in the Colorado Rockies.
The 42-year-old, of Rothwell, Leeds, suffered from altitude sickness during the 95-minute climb.
She said she just felt relief at having reached the summit.
Mrs Tomlinson said: "Trying to drink enough liquids to stay hydrated is very difficult, but it's been good.
"We've still got to go down, but that's a mere hop, skip and jump compared to what we've done."
Earlier she said the ride had been much tougher than she had imagined. "So far the Rockies have been easier than the mountains on Nevada and Utah but my legs are suffering from the constant climbing.
"I'm still going although I'm not quite sure how after some of the days.
"It's one day at a time at the moment. It's hard to believe that we've already nearly cycled the distance from John O'Groats to Lands End twice."
Mrs Tomlinson, whose heart only functions at 49% due to her intensive treatment regime, has suffered severe tiredness, nausea and nose bleeds as a result of altitude sickness during the climbs so far.
Her husband Mike, 45, who is following her in a support vehicle with their nine-year-old son Steven, said: "There have been times since the start when it has looked like the ride was over.
"On Tuesday this week after nine consecutive gruelling days of massive climbs in extraordinary heat it did look as though the end was near as she finished the 86-mile stage in tears and hunched over her handlebars.
"Since then she's dug particularly deep and continued despite not being particularly well."
Mrs Tomlinson started her challenge in June with co-riders Ryan Bowd, 27, of Calgary, Canada, and 40-year-old Martyn Hollingworth, of Aviemore, in the Scottish Highlands.
The trio hope to finish in New York by September.