"She's already gotten some of the benefit from it. She may already have gotten most of the benefit for it," he said, explaining that patients who stick with tamoxifen reduce the risk of recurrence by about 50 percent. "I wouldn't advise it, I'd advise her to finish the whole course, but she's probably reduced her risk of recurrence some already."
Gorski said he believes that many unproven alternative treatments exist in breast cancer because the course of the disease can be very different in different people.
"The aggressiveness of breast cancer can be incredibly variable, ranging from very rapid growth to percolating along for years on end," he said.
He also said that the mother's cancer has already been removed, with the tamoxifen serving as an adjuvant therapy -- designed to prevent recurrence rather than cure the disease -- and so, the outlook may be positive even with unproven treatments.
As a physician who hears requests from breast cancer patients for alternative therapies, Dr. Marisa Weiss, founder of breastcancer.org, said the key is understanding patient concerns and not losing dialogue, even if the patient chooses an unproven route.
"Basically, I would say to them, clearly you've made this choice to do alternative medicine, and I believe I've told you everything I can based on these studies and experience. I can't force you to do it, but let's choose a time to re-evaluate," said Weiss.
She said while a patient might ignore a doctor's advice, keeping the dialogue preserves the relationship in the event the patient changes their mind and chooses to go with conventional therapy.
Coscarelli notes that something similar holds true for families of patients who shun conventional medicine.
"I think it's sometimes really hard to allow people to make their own decisions when you disagree with them," she said, noting that she has seen these conflicts in her work, between relatives and spouses.
"There's a lot of appraisal that goes on for individuals, said Coscarelli. "This daughter and mother have a real conflict in belief systems, and ultimately the mother gets to make the decision about her own body. The important thing would be to not let the decision deteriorate their relationship. There's a limit to what the daughter can do."
She recommended that someone in Grace's situation can try and provide education, probably by having her mother speak with someone who is "bilingual," versed in both Western and alternative medicine methods.
But ultimately, the decision will be out of Grace's hands.
"Ultimately, this mom's going to determine her own treatment, and the daughter's going to need to be able to accept that," said Coscarelli.