Survival chances of people diagnosed with early stage lung cancer are much worse for those living in poorer communities, new analysis suggests.
The Welsh Cancer Intelligence and Surveillance Unit (WCISU) figures show 72% of those diagnosed with stage one lung cancer survive the first year in the most deprived areas.
But the survival rate is nearly 90% in the least deprived areas.
The report covers 22 cancers, including the five most common in Wales.
No such inequality in lung cancer survival was found within stages two, three, and four.
For bowel cancer diagnosed at stages one to three, people living in areas of greater disadvantage tend to have increasingly lower survival rates although there is not as big a difference as with lung cancer.
With breast cancer, survival is universally high at the early stage but a gap emerges between the least and most disadvantaged areas for stage three breast cancer.
It has long been believed that there is poor recognition of the signs and symptoms of cancer, in particular in more disadvantaged communities.
Others may be reluctant to see their GPs because they are worried about "wasting the doctor's time" or believe symptoms will "go away", the report found.
It also shows that one-year survival for early and later stages of diagnosis varies considerably between different types of cancer.
Breast and prostate cancers have among the highest one-year survival when they are diagnosed at stage one. Lung and liver cancers have among the lowest.
For many cancers analysed, the largest fall in survival happens when they are diagnosed at later stages.
So prostate cancer survival remains at 100% for stages one to three, but then falls to 84% at stage four.
Bowel cancer survival also drops dramatically when diagnosed between stages three and four, falling from almost 88% to under 39%.
You might be interested in these stories:
Dr Tracey Cooper, chief executive of Public Health Wales and chairwoman of the Cancer Implementation Group for Wales said: "While many factors affect survival, including the type of cancer and the presence of other underlying health conditions, these new statistics clearly demonstrate the significant benefits of early diagnosis for patients for some types of cancer."
She said the report was "essential" to the work supporting NHS Wales in improving the outcomes and experience for people with cancer.
Dr Dyfed Wyn Huws, director of WCISU, said it was the first time national population-based one-year survival figures had been published by each stage of diagnosis.
"From now on, and in future years, we aim for our cancer staging data to continue to improve in order to help us highlight any changes in earlier diagnosis and cancer survival by each stage for the whole population, as well as for health board areas," he said.