Sad news for pop star Anastacia.

The 44-year-old singer has been diagnosed with breast cancer, causing her to cancel her upcoming European tour, according to US News.

The singer had successfully battled breast cancer back in 2003, but it has sadly returned.

Her European tour was scheduled to begin in London on April 6, but that and all future touring has been suspended for the time being.

Anastacia is hugely popular in Europe and Australia, having sold more than 20 million albums worldwide.

We're wishing Anastacia the best and hoping that she'll be cancer-free again soon!

Source: US News