Facebook came under fire last week after it removed a breast cancer awareness advertisement by Swedish nonprofit organization Cancerfonden. The advertisement was an illustrated guide that showed women how to examine their breasts and depicted stylized cartoon versions of breasts.

The ad was taken down by Facebook shortly after it was posted Thursday. Cancerfonden then submitted a second ad, this time showing breasts as two blurry, cartoon squares. The organization explained that it made “the breasts in the picture square in order to emphasize the absurdity of Facebook’s decision.” Facebook also removed the second ad, citing that it didn’t comply with company policy.  Facebook’s guidelines only prohibit adult content that is explicit, suggestive or sexually provocative.

Cancerfonden posted an open letter Thursday on its website condemning Facebook’s decision to take down both ads. “We understand that you have to have rules about the content published on your platform,” the letter acknowledged. “But you must also understand that one of our main tasks is to disseminate important information about breast cancer. That the important knowledge dissemination is not allowed by Facebook is unfathomable.”

After the open letter circulated, Facebook issued an apology to Cancerfonden and reposted the ad on Friday. “We are very sorry,” Facebook said. “Our team assesses millions of advertiser images every week and sometimes we prohibit ads improperly.” The company added that the image didn’t actually violate its policy.

It’s not the first time Facebook has been the target of an open letter as the result of overly censorious behavior. In September, Norway’s largest newspaper, Aftenposten, wrote an open letter to the company after it removed a photo the paper had posted of the famous “napalm girl.” The image shows a naked child, Kim Phuc, fleeing a napalm bomb during the Vietnam War.

“If you will not distinguish between child pornography and documentary photographs from a war, this will simply promote stupidity and fail to bring human beings closer to each other,” wrote Espen Egil Hansen, editor-in-chief and CEO of Aftenposten. The letter spurred the hashtag #DearMark as a way to reach Facebook founder Mark Zuckerberg.

Facebook announced it would change its banned image policy Friday, the same day it re-posted Cancerfounden's advertisement. The company explained that moving forward, it would allow otherwise banned imagery if it was newsworthy or significant. "In the weeks ahead, we're going to begin allowing more items that people find newsworthy, significant, or important to the public interest - even if they might otherwise violate our standards," Facebook said in a statement about the policy change.