LONDON (CNN) -- The slightly increased risk of cancer and heart disease faced by women who take oral contraceptives may be gradually reduced after they stop taking them, British researchers said on Thursday.

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In a 25-year study of women who used oral contraceptives, commonly known as "the pill," the researchers found that 10 years or more after women stopped taking the pill, the extra hazard was negligible.

However, women who were current or recent users did face a slightly higher risk of disease, the team from the Imperial Cancer Research Fund and the Royal College of General Practitioners said.

"Our results suggest that most of the effects of oral contraceptives on mortality occur in current or recent users and that few, if any, effects persist 10 years after stopping use," Professor Valerie Beral of the Radcliffe Infirmary in Oxford and colleagues wrote in the British Medical Journal.

"I think it's very good news," Dr. Robert Hatcher, author of Contraceptive Technology, told CNN. "The number one question women have asked about (birth control pills) since 1960 is do they cause cancer. This study shows there is no long-term risk."

More than 300 million women around the world have used oral contraceptives since their introduction in 1959.

Look at long-term effects

While the short-term health effects of the pill are well documented, the British study is one of the largest and longest undertaken on its long-term effects.

In their study, the British researchers tracked the health of 46,000 women between 1968 and 1993. Half of the women used the pill at the start of the study and half did not.

During the study 1,599 of the women died, but this was less than the average death rate for the British population as a whole.

The researchers confirmed earlier studies showing that the incidence of breast cancer was slightly higher among current and recent users of the pill, compared with women who did not use oral contraceptives at all.

But this risk was negligible 10 or more years after women stopped using the pill.

"Our results are consistent with this finding (on breast cancer) and suggest that other cancers of the female reproductive organs may also be affected by current and recent use of oral contraceptives but may wear off after use stops," the researchers wrote.

Further data is needed to confirm the findings, they added. "Continued follow-up ... will yield important information for the many millions of women throughout the world who have used oral contraceptives," they said.

The researchers said they were making no new recommendations based on their findings.

Reuters contributed to this report.