LONDON (Reuters Life!) – Survival rates for four major cancers diagnosed between 1995 and 2007 are higher in Australia, Canada, and Sweden than in Britain and Denmark, according to an international study published on Wednesday.

The difference in survival rates for breast, ovarian, colorectal and lung cancer are largely due to tumors being detected later in Britain and Denmark, researchers said, which makes the cancers more difficult to treat.

"these data will be crucial in helping all the partners involved improve their cancer outcomes," said Mike Richards, the British government's national cancer director for England, who worked on the study with Michel Coleman of the London School of Hygiene and Tropical Medicine and 80 others.

The study was funded by the UK government's department of health and the charity Cancer Research UK.

Richards said his department was already working on improving earlier diagnosis by giving doctors more direct access to key diagnostic tests, and will launch a campaign next month to alert people to the early signs and symptoms of bowel, lung and breast cancer.

Previous findings have shown that for patients diagnosed with cancer from 1995 to 1999, up to 11,400 more patients died each year within five years of diagnosis across England, Scotland and Wales than would have been the case if five-year cancer survival rates had matched the highest in 13 other European countries. Breast, ovarian, lung and colorectal cancers accounted for half of those avoidable deaths.

Since the late 1990s many countries have implemented new cancer plans, including Britain and Denmark, to try to raise survival rates to the levels seen in other wealthy nations.

Wednesday's study, published in The Lancet medical journal, found that relative survival improved during 1995-2007 for all four cancers in all the countries studied.

Survival was persistently higher in Australia, Canada, and Sweden, intermediate in Norway, and lower in Denmark, England, Northern Ireland, and Wales, particularly in the first year after diagnosis and for patients aged 65 years and older.

International differences narrowed at all ages for breast cancer between 1995 and 2007, from about 9 percent to 5 percent — with the range for one-year survival across the six countries at 89-98 percent for 1995 to 1999 and 93-98 percent for 2005 to 2007. For five-year breast-cancer survival, differences between countries narrowed from 14 percent to 8 percent. Survival ranges narrowed less, or not at all, for the other three cancers.

"Differences in individual, health-system, and clinical factors — such as public awareness of cancer, diagnostic delay, stage (of cancer at diagnosis), comorbidity (other serious illnesses at the time of cancer diagnosis), and access to optimum treatment — are all potential explanations for the overall differences in relative survival," the researchers wrote.

(Reporting by Kate Kelland, editing by Paul Casciato)