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Quitting smoking as a predictor of impending disease
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The article by Campling and colleagues, “Spontaneous smoking cessation before lung cancer diagnosis,” in the April 10 issue of HemOnc Today introduces an interesting hypothesis to the realm of tobacco use and its relationship to disease. The authors use retrospective data from 115 patients with lung cancer to determine the relationship between spontaneous smoking cessation and time to lung cancer diagnosis. The results indicate that smokers quit spontaneously with much more proximity to a diagnosis of lung cancer than that of prostate cancer or myocardial infarction. They report that the commonly held belief that smokers quit before lung cancer diagnosis due to symptoms that they begin to experience may not always be the case. In addition, their data show that people who develop these diseases often quit smoking with relative ease, again in contrast to generally held beliefs.
The authors concede that there are certain weaknesses and biases associated with their findings and that this is a small sample to draw definitive conclusions. These data are dependent on patient recall, comparison groups are not entirely matched, especially regarding the very nature by which these diseases are detected and their natural history, and there were some variables that are traditionally linked to cessation that were not mentioned in the analysis (eg, education, socioeconomic status, psychiatric and behavioral comorbidities). In addition, some unusual results call into question the generalizability of the findings, such as the unexpectedly low level of severity of withdrawal symptoms reported by former smokers across all disease groups (mean 2.8 for lung cancer; 1.9 for prostate cancer; and 2.4 for myocardial infarction on a 0-10 scale or severity). However, despite this, the proposed hypothesis is worth consideration. There is at least some biological plausibility for the hypothesis that certain substances produced by lung cancer cells may directly or indirectly affect nicotine’s effects in the brain as outlined in the study’s discussion, thus affecting smoking behavior.
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No other single intervention has the potential to reduce cancer mortality more than eliminating tobacco use. Tobacco use results in one-third of all cancer deaths in this country. The overwhelming majority of tobacco users want to quit. Despite the findings of this study, many are unable to quit on their own and typically less than 5% are successful in quitting “cold-turkey.” Safe and effective treatments exist and are outlined in the US Public Health Service Clinical Practice Guidelines, Treating Tobacco Use and Dependence. These treatments can double or triple success and should be considered in all smokers, especially those at risk of other medical illnesses. Despite this effectiveness, tobacco treatments are woefully underutilized, and coverage for these treatments is nowhere near those of other medical conditions, such as diabetes.
Although this analysis focuses on smokers who quit before developing diseases such as cancer and heart disease, physicians must be aware that approximately half of all smokers continue to smoke after developing cancer or suffering a myocardial infarction. Efforts need to emphasize the importance and benefit for these smokers to stop using tobacco, despite their seemingly inability to do so on their own. Again, the role of tobacco dependence treatments among smokers with medical illnesses is critical and possible with appropriate treatment.
There are several clinical implications of the current study. First, the presentation of a longstanding smoker (mean 44 years of smoking in this study) who spontaneously stops smoking with no apparent reason should at least raise a question. It is frequently puzzling in the clinical practice of tobacco dependence treatment to understand why after 40-plus years of smoking, one decides to quit today. This study suggests that in at least some cases, the answer may be an underlying pathological effect and might point to an increased risk for a cancer diagnosis. This is not to say that all smokers who decide to quit should undergo an overly comprehensive diagnostic workup. There are many public health factors that have recently been introduced in medical settings and the general public encouraging cessation and increasing awareness of treatment resources. Additional interventions, such as clean indoor air laws, facilitate consideration of quit attempts. Therefore, there are many reasons why smokers who are exposed to these environmental cues on a regular basis might attempt to quit at a given time besides impending cancer.
Another implication has to do with the recent data regarding the potential benefit of screening for lung cancer by CT scanning. Although the data are not fully conclusive, there seems to be a potential benefit to screening smokers of 30 pack-years or more who are aged 55 to 74 years, based on data from the National Lung Screening Trial. Perhaps, in addition to considering screening all smokers meeting these criteria, asymptomatic smokers who spontaneously quit smoking should also be screened, as they may be at risk for a future lung cancer diagnosis.
There is not enough evidence based on the data presented by Campling and colleagues to recommend any specific changes in clinical practice at this time. However, further data could be useful to evaluate the relationship of spontaneous cessation and subsequent development of malignancies. The overall message regarding tobacco use and medical complications should continue to be: 1) It is never too early or too late to stop using tobacco; 2) Regardless of how long you have smoked or what medical conditions you currently suffer, quitting can improve your health, medical outcomes and quality of life; 3) Effective, evidence-based treatments exist for tobacco dependence and should be considered with all tobacco users.
Michael B. Steinberg, MD, MPH, FACP, is director of the UMDNJ-Tobacco Dependence Program. He reports no relevant financial disclosures.
For more information:
- Aberle DR. Radiology. 2011;258:243-253.
- Fiore MC. Respir Care. 2008;53:1217-1222.
- Steinberg MB. Ann Int Med. 2008;148:554-556.
- Steinberg MB. Ann Int Med. 2009;150:447-454.