Professional Breast Cancer Consulting & Advocacy

Devoted to Helping You from Diagnosis through Survivorship

Welcome to By Your Side LLC. I am a licensed, certified oncology nurse practitioner in Washington State, with over 35 years of experience in oncology patient care, research and women’s healthcare. I am devoted to helping individuals through breast cancer treatment from the moment of diagnosis, through the months and years that follow. Whether you have just heard the words “You Have Breast Cancer” or you are struggling with issues following your treatment, I am a knowledgeable, compassionate professional and have designed a practice that is ready to help you.

Giving You the Tools to Make Sound Treatment Decisions

My philosophy of care at By Your Side emphasizes listening and addressing your concerns, recognizing that your cancer diagnosis is just one aspect of your life and does not define who you are. I believe that knowledge is a powerful tool for making sound treatment decisions and that respect for each person’s values and personal goals is central to exceptional care.

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“Muff Heffernan was a godsend for me, and my husband, after I was diagnosed with breast cancer last year. Hearing the words “You have invasive lobular cancer” was frightening and I didn’t know where to turn to navigate through all the information and options. Muff went to appointments with us and afterwards, calmly explained everything in non-medical terms. When there were decisions to be made, she simplified them and helped guide us to the right answer. I had confidence in my decisions because of her knowledge and wisdom. Today I am cancer free, but I can’t imagine going through this experience without Muff and her expertise.”

– Sue, Breast Cancer Survivor

“When I was diagnosed with breast cancer in October 2019, my husband and I were completely at a loss as to how to proceed, ie. how to reach out to physicians, which area hospital and team was the best fit for our needs, and simply what was the next step after the diagnosis. Muff listened to my story with care and compassion and because of her extensive professional background was able to calmly present us with a list of providers, logistics and next steps to begin the path to treatment. She made phone calls on our behalf and greatly eased the way forward. Muff was an invaluable lifeline in a very unsettling time for us, and my husband and I are extremely grateful.”

– Nora, Breast Cancer Survivor

“By Your Side-Unbelievably Helpful! Muff Heffernan was there for me from start to finish! She is able to connect you to all of the right providers and resources. She has a vast knowledge of breast cancer and explains things to you in very understandable terms. She helps you navigate your unexpected diagnosis in a calm and professional way. Her caring and compassionate, empathetic manner is so supportive. I could not have gotten through this without her!”