Beating Bowel Cancer found wide variation within the NHS in England in diagnosing the disease.
It says 3,200 lives could be saved each year if every NHS region did as well as the best performing areas.
In some regions, less than a third of cases are detected before the cancer has started to spread around the body.
Part of the problem is people not coming forward for checks.
A bowel-cancer screening programme was introduced in England in 2006, but figures show that uptake among the eligible 60- to 74-year-old age group has been around the 60% mark.
Early detection is vital.
Those diagnosed with the disease in its advanced stages have a 7% chance of living another five years.
This compares with a 97% chance of survival if the cancer is detected at the earliest possible stage.
The regional diagnostic figures quoted by Beating Bowel Cancer come from the National Cancer Intelligence Network's Cancer Commissioning Toolkit.
It captures data from more than 150 Clinical Commissioning Groups (CCGs) caring for hundreds of thousands of NHS patients.
Mark Flannagan, chief executive of Beating Bowel Cancer, said: "It's unacceptable that there are CCGs in England that diagnose less than one in three patients at an early stage.
"If they all performed as well as the best, thousands of lives could be saved and millions of pounds could be freed up to be used for other bowel cancer treatments, which patients are frequently told are unaffordable.
"This will require further improvements in screening, renewed efforts to raise awareness of signs and symptoms, and investment to support improvements in GP performance in investigating and referring patients appropriately."
In the UK, about 41,000 people are diagnosed with bowel cancer each year and about 16,000 die of the disease.
Nick Ormiston-Smith of Cancer Research UK said: " There are a number of reasons why cancer may be diagnosed at an advanced stage - for some cancers, symptoms are often only noticeable once the tumour has already started to spread. But for many others there are chances for the cancer to be picked up earlier.
"It's vital that people are aware of their body and if they notice anything unusual they should visit their GP."
The main symptoms to look out for are:
Thousands of people in England are dying from bowel cancer because their disease is not being spotted early enough, a charity has warned.