Jessica Chastain updated fans about the health of her grandmother, Marilyn Herst.

The 47-year-old actress and film producer recently took to her official Instagram account to share that her grandmother has been diagnosed with breast cancer.

Chastain began her post with, "My beautiful grandma Marilyn, who many of you have met at different events, was recently diagnosed with breast cancer."

The Mothers' Instinct star went on to say, "This week, I flew to meet with her amazing doctors and surgeons who are providing her the best possible care. I’m beyond grateful to the incredible hospital staff.”

“She’s a total badass, and I know she’ll get through this," Chastain gushed over her grandmother.

"In honor of Breast Cancer Awareness Month, she asked me to remind all of you: schedule your mammogram today. You are so important to so many people—please make this a priority. #BreastCancerAwareness #GetChecked #EarlyDetection," the actress added.

Moreover, the Oscar winner also posted a video, sharing details of how Herst's cancer was diagnosed when she felt a small lump.

"I feel so grateful for the fact that I found it so early because it's so treatable, but if you don't take care of yourself and check yourself or even have your regular mammograms, you may not catch it early and it may not help you," said Herst.