Lung cancer, which has been long regarded as a man's disease, is now the leading cause of deaths among women in developed countries.

Breast cancer was formerly the top killer of women and because of its name is inextricably linked to females.

A new study published online in CA: A Cancer Journal for Clinicians said the rise of lung cancer reflects changing smoking patterns among females worldwide. It's the result of a surge in smoking among women that began four decades ago.

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"The lung cancer deaths we are seeing today really have to do with smoking trends we saw in the 1970s, when women really started to pick up smoking," said Lindsey Torre, an epidemiologist at the American Cancer Society.

Lung cancer has been the leading cause of cancer deaths among men in developed countries for decades. It's also been the leading cause of cancer death for U.S. women in past years.

Worldwide, lung cancer is the most common cause of cancer-related death in both men and women, however. It causes 1.6 million deaths annually as of 2012.

Today, smoking causes nearly 9 out of 10 lung cancer deaths.

The fatal effects of smoking, however, aren't immediately apparent. It takes from two to three decades to see lung cancer deaths due to smoking, because lung cancer takes a long time to develop.

Unfortunately, lung cancer death rates worldwide continue to rise. In the United States, however, the death rate from lung cancer has leveled off, said Torre.

Lung cancer is also the leading cause of cancer deaths for men in developing countries. Breast cancer remains the main cause of female cancer deaths in developing countries.

In developing countries, lung cancer rates and deaths are expected to rise with many more young men and women taking-up smoking.

There is good news for women, however. Lung cancer rates in developed countries will fall over the next 30 years, according to Torre.