The 41-year-old Dutch-born singer revealed her diagnosis in a social media post yesterday (Wednesday, October 26).

She wrote: "A letter to you, Life comes in waves, with ups and downs. I have had the joy of riding many highs, and I have shared these with you through social media and the many many shows worldwide throughout the many years of my career.

 

"But now a new wave hit me. Not a good one. I have breast cancer. It was diagnosed a little over 2 weeks ago and I will have surgery tomorrow to remove the tumor. My prognosis is very good!!! It seems to be a non-aggressive cancer, which seems to not have spread. I will keep my breast. And I will be cancer free after this surgery, plus a local radiation treatment that will take place three months after this surgery, hopefully. We will know more after the surgery to see if this positive prognosis stands.

 

"The word cancer is a shocker. All that you found important in life before this diagnosis changes radically within minutes. Now I just want to be healthy again. I want to see my daughter grow into a woman; I want to live! And the scariest part of this diagnosis is that I thought I was healthy! I didn't feel the cancer, I didn't know it was there until I, as a 40+ woman, went to a standard mammogram checkup. Something many countries offer, for free even for the lucky ones. Had I not gone there, the tumor would have gone undetected. In a year from now this could have grown much bigger. The thought of that makes me share this story with you. A mammogram is lifesaving! It's uncomfortable and you might think that you won't have something in your breasts anyway but GO! And for the men reading this: remind your wife, girlfriend, mother, sister to go and get checked. Even without the luxury I as a western woman experience with free mammogram checkups: GO! Luckily, there are many organizations that offer information about self-detection if you do not have access or funds for a mammogram.

If I might inspire you to take good care of yourself, then something good will come out of this cancer diagnosis.

 

"If all goes as planned, I will be up and running in time for the European tour with NIGHTWISH, that will start on the 20th of November! And I am optimistic since my prognosis is good!

 

"I promise to take good care of myself.

 

"I will be off the grid for a while to focus on myself."

 

Jansen made her live debut as the frontwoman of NIGHTWISH on October 1, 2012 at Showbox Sodo in Seattle, Washington following the abrupt departure of the band's lead singer of five years, Anette Olzon. Jansen officially joined NIGHTWISH in 2013.

 

As part of NIGHTWISH, Jansen landed two number one albums in Finland, and Top Five albums in Austria, France, Germany, Greece, Hungary, the Netherlands, Norway, Sweden and Switzerland.

 

Born in the Netherlands, Jansen joined her first band, one of the world's first symphonic metal bands, AFTER FOREVER, when she was only 16 years old. The group went on to release five albums from 2000 to 2007, before they broke up in 2009.

 

Jansen's next band, REVAMP, released two albums in 2010 and 2013, before she joined NIGHTWISH as a full-time member. NIGHTWISH's first album with Jansen as the lead singer was 2015's "Endless Forms Most Beautiful", which landed in Top 10s around the world. This was followed by 2020's "Human. :II: Nature." , which was also an international success.

 

Jansen has toured extensively with the band and appeared on three of NIGHTWISH's live albums "Showtime, Storytime", "Vehicle Of Spirit" and "Decades: Live In Buenos Aires".