What do we know for sure about the health implications of inappropriate weight and nutrition? We know that approximately 60% of US adults currently are considered overweight or obese and approximately 300,000 deaths a year in this country are associated with overweight and obesity. And, most importantly for this discussion, we know that randomized controlled trials suggest that lifestyle changes resulting in the loss of excess weight reduce the risk cardiovascular disease, lower blood pressure, lower blood sugar, and improve lipid levels. In essence, there is a chain of evidence: A medical condition exists, the condition causes adverse outcomes, with interventions the condition can be reversed, and the problems it causes can be ameliorated.
The Available Data
Dr. Colasanto et al present a detailed picture of existing data on the other side of the nutritional coin. They initially discuss the etiology of weight loss in head and neck cancer patients. It is worth emphasizing that many victims of head and neck cancer facilitated the development of their cancer by a prior lifestyle characterized by heavy alcohol(Drug information on alcohol) and tobacco use that often is associated with an unhealthy diet. Thus, many head and neck cancer victims begin their fight against cancer already nutritionally deprived. But, this just adds to the authors' rationale.
They then review the available evidence relating malnutrition to poorer outcome of cancer therapy. However, the authors are handicapped because the available data are less than totally convincing. For example, they cite the data of Lopez et al as demonstrating "an association between weight loss and inferior outcome for the head and neck cancer patient." But in the Lopez report, "nutritional status [was] indicated by the presence or absence of the cutaneous delayed hypersensitivity response"-a measure that does not spring to my mind as a sine qua non of nutritional status.
They also cite the data of Bosaeus et al, which associates weight loss and survival. Here, too, the data are difficult to translate for patients who are receiving curative therapy for head and neck cancer, because it was obtained from patients who had a spectrum of metastatic cancers and were receiving only palliative care. Moreover, it is not clear to me from these reports whether the weight loss contributed to diminished survival, or both accelerated weight loss and decreased survival simply are secondary manifestations of more aggressive tumors.
To further complicate matters, any association between weight loss and decreased survival may be a generalized effect and not due to cancer per se. In a recently reported prospective randomized trial of patients with stage II or III rectal cancer, underweight patients had an increased risk of death compared with normal-weight patients but no increase in cancer recurrences. If this observation applies equally to head and neck cancer, the current trend of using percutaneous endoscopic gastrostomy (PEG) tubes routinely only for patients who have high-risk cancers and are scheduled to receive an aggressive regimen may be myopic in its focus.
Acting Prudently When Faced With Unconvincing Evidence
Dr. Colasanto et al then provide a very good review of detailed recipes for management of underweight patients. Unfortunately, their review necessarily stops at that point, leaving the reader to assume that, or wonder if, the principle established for overweight individuals—ie, that restoration of a "healthy weight" is beneficial—also applies to underweight head and neck cancer patients. Certainly this seems reasonable. Clinically, many of us are convinced that the provision of "adequate"nutritional support during treatment allows patients to tolerate aggressive therapies that they would not be able to withstand otherwise. Yet in this age of evidence-based medicine, the data to prove that such support translates into lives saved or cancers cured are weak or worse.
The American Cancer Society (ACS) recently convened an expert panel to review and discuss "nutrition and physical activity issues during the phases of cancer treatment and recovery." For any of the four most common types of cancer (breast, colorectal, lung, and prostate), these experts concluded that none of the available data about nutrition and cancer rose to a level that could be interpreted as "convincing evidence for a benefit" in terms of preventing cancer recurrence, improving overall survival, or promoting quality of life! For head and neck cancers, the experts could only suggest, "In the absence of more definitive information, survivors... should strive to follow the ACS nutrition and physical activity guidelines for the prevention of cancer."
Dr. Colasanto and colleagues are to be thanked for their detailed review of the steps that can (and in the current state of knowledge likely should) be taken to combat weight loss in the face of head and neck cancer. At the same time, we should be aware that weight loss associated with head and neck cancer and its treatment may simply be an associated phenomenon, a surrogate for the aggressiveness of the tumor and not a primary cause of morbidity and/or mortality. Measures taken to improve nutrition may not directly improve outcome. As a community, we need to remind ourselves that the interventions reviewed by Dr. Colasanto et al have a physical and monetary cost that should not be borne indefinitely without proof that they truly are ben eficial. Wouldn't someone like to conduct a prospective clinical trial?