Every year around October, when the autumnal Jewish holidays and the fall foliage simultaneously reach their respective peaks, I confront a dilemma as a religious physician. Particularly as Yom Kippur approaches, a sense of solemnity envelops many Jews. Suddenly, the existential questions of "who shall live and who shall die" seem to reverberate with greater amplitude. Although few will admit it, many avowed secularists begin to wonder whether there truly is a Book of Life that is being inscribed by a divine author. In a country where practically one in three Jews identifies as completely nonobservant, surveys indicate that nearly 90 percent of the population performs at least some of the rituals on this holiest day of the year. For me, these Days of Awe revolve around my fear that I will be asked by my cancer patients, "Doc, should I fast?" During three decades of practice as an oncologist in the US and abroad, I have developed a comfort level in advising folks about risky modalities like chemotherapy and radiation treatments. But the fasting question is much more challenging than the usual inquiries about the side effects of a specific drug or even the cure rates associated with a given regimen. When attempting to respond to this query, I am reduced to an inexperienced rookie. Why do I feel ill-equipped to answer a legitimate question from a well-intentioned person? WHEN PEOPLE under my care inquire about fasting, I wonder if they are signaling something that evades me. For instance, since recent studies have asserted that most patients silently wish that physicians would address their spiritual well-being, am I being alerted to a religious awakening that is taking place? I am also curious if this could be an effort to invoke an unconventional therapeutic tool, as indeed a classic article from the prestigious M. D. Anderson Hospital in Houston demonstrated that more than 80 percent of cancer patients seek complimentary and alternative medicines. If a religious patient prefers not to fast on Yom Kippur, is he announcing that he has thrown in the towel, or is he merely worried about the consequences of no nutritional intake? Could the decision to fast or even the decision not to fast simply represent an attempt to regain control of a life that seems to have sputtered away from any semblance of order? As one who endeavors to respect the mores of patients, I tend to activate safeguards to protect against imposing my value system on others. My agenda does not include preying on the vulnerable to cultivate a flock of born-again religionists who wish to return to their faith. How does one sort through this entanglement to help patients? It turns out that this is not a new conundrum. In the Babylonian Talmud (Yoma 83a) we read that "Rabbi Yanai asserted that when a sick person feels he must eat on the Day of Atonement but his physician opines that it is not necessary for him to eat, we side with the patient, for it is written in Proverbs [14:10] that the heart knows the bitterness of its soul." This patient-centric stance belies the fact that the statement was uttered nearly 2,000 years ago. RESPECT FOR the core values of a patient is the centerpiece of the Medical Humanism movement that has gained traction in modern health care. In an editorial that appeared in the New England Journal of Medicine earlier this year, Hartzband and Groopman pointed out that another pillar of this worldview is the notion of "shared decision-making," which connotes a commitment on the part of both parties in the doctor-patient dyad to listen carefully to the priorities of the other. Toward this end, I have recently resolved to expand the dyad into a triad by bringing a rabbi into the equation. In Israel, rabbis have hardly assumed the pastoral role that Americans have come to expect from their clergy. Rather, rabbis who are hospital-based have historically restricted their attention to noncontroversial tasks such as checking that the food on meal carts is kosher and that every room is adorned with a mezuza. Fortunately, despite the fact that there is still no Hebrew word for "chaplain," Israeli rabbis have suddenly become interested in playing a significant role in the therapeutic arena. By inviting rabbis to become active players, patients gain access to a comprehensive sounding board to reach decisions. Such three-way consultations are often emotionally charged, as each protagonist exposes deep concerns in trying to figure out what is best for the cancer patient when it comes to fasting and many other matters. Usually there is a sense that a sacred bond has been formed. At present, I have no outcome data to report from this experiment, but I am pleasantly surprised to learn that I have finally come up with a new year's resolution that I can live with. The writer is the chairman of the Department of Radiation Oncology at the Tel Aviv Medical Center and the founder of Life'sDoor.org.