Bernie yesterday announced that she is suffering from the disease, but said that she would not let the illness defeat her.
Speaking to The Mirror, Coleen confirmed that the Nolan family is determined to support Bernie throughout the battle ahead.
The Loose Women star commented: "She's so strong, she's really holding it all together. Obviously she's had her moments but she's strong and we all have to be strong for her. We've all been rallying round to help her.
"Once her treatment starts if she's not feeling well, one or two of us will be there to help with her daughter Erin and her husband Steve."
Bernie is the third Nolan sister to be diagnosed with breast cancer. Anne and Linda previously fought the disease in 2000 and 2006 respectively.
