The main goal of the current study was to examine associations between smoking status and several indices of pain reporting among groups of nonsmokers, former smokers, and current smokers who were previously diagnosed with cancer. We further sought to explore potential relations between pain and smoking behavior, including number of years since quitting and number of cigarettes smoked per day.
As hypothesized, and consistent with Daniel and colleagues (2009), patients in the current sample who continued to smoke despite their cancer diagnosis reported greater pain severity than patients who were identified as lifetime nonsmokers. Although former smokers’ pain scores did fall between those of nonsmokers and current smokers, they did not differ significantly from either. Due to the cross-sectional nature of these findings, it is unclear whether smoking may have increased pain or been motivated by the pain experience itself. Indeed, there is some empirical support for both causal directions. First, although true causal effects have yet to be established, research indicates that smoking may serve as a marker and/or risk factor for the incidence and severity of chronic nonmalignant pain (for review see [10
]). For example, it has been proposed that tobacco smoke may increase pain by reducing blood and oxygen flow to peripheral tissues, or via direct influence on the neurological processing of sensory information. Second, for over two decades researchers have suggested that the avoidance and relief of pain may be a potent reinforcer in the maintenance of tobacco dependence (e.g., [13
]). Whereas evidence is mixed regarding the acute pain-inhibitory effects of nicotine (e.g., [14
]), mounting cross-sectional [17
] and causal data [10
] indicate that pain can nevertheless be a potent motivator of smoking behavior.
Also as predicted, significant associations were observed between smoking status and the degree to which pain interfered with the daily routine of persons with cancer. Specifically, patients who continued to smoke despite their cancer diagnoses reported greater interference from pain than either former smokers or never smokers. No differences in pain interference ratings were observed, however, between former smokers and never smokers. This finding suggests the possibility that pain may be experienced as less obtrusive if cancer patients either quit smoking or never initiated tobacco smoking in the first place.
Contrary to our predictions, results revealed no differences in the extent to which cancer patients experienced psychological distress associated with their pain as a function of smoking status. Examination of the means in indicates that although smokers endorsed somewhat greater pain-related distress than former smokers and never smokers, all patients reported relatively low levels of distress. Another possible explanation for these non-significant findings is that continued smoking may have served as a means for persons with cancer to cope with pain-related distress. Indeed, stress-coping [34
] and self-medication [22
] models of addiction motivation propose that individuals use substances to cope with distress by regulating affect [4
], facilitating distraction [3
], or enhancing performance [18
]. An important clinical implication of this consideration is that cancer patients who become increasingly reliant on tobacco for stress-coping and self-medication may become less motivated to quit smoking.
A particularly interesting finding of the current study was the inverse relationship between number of years since quitting smoking and reports of pain severity/pain interference among our sample of former smokers. Although these findings are correlational and modest in magnitude, they could have important clinical implications, particularly if replicated in future studies that are capable of establishing causality. For example, psycho-educational interventions for smokers who have been diagnosed with cancer would likely benefit from conveying scientific evidence that quitting smoking may result in significantly reduced pain over time. However, it is equally plausible that reduced pain preceded and increased the probability successfully quitting smoking. Clearly, additional research is warranted.
The lack of association observed between the number of cigarettes smoked per day and pain severity, pain interference, and pain-related distress may suggest the absence of a dose-response influence of cigarette consumption on pain-related outcomes. However, it is important to note that such presumptions would be limited to the current sample.
Also notable was the finding that a significantly greater percentage of both never smokers (87.5%) and former smokers (73.1%) had undergone surgery than did current smokers (44.4%). Considering that smoking has been associated with increased risk of complications and poorer recovery [23
], patients may have been instructed to quit smoking as a prerequisite for undergoing surgery. However, this explanation does not address why never smokers were more likely to have undergone surgery. Clearly, this finding requires replication and further examination.
The present study has several important limitations. First the use of cross-sectional data precludes us from making causal inferences. Although these findings have served to identify variables that warrant additional empirical attention, conclusions regarding their relative importance would be premature. Whereas we have made a point of discussing clinically relevant issues germane to the topic of pain and smoking among cancer patients, further deliberation regarding potential clinical implications should be reserved for more conclusive findings. For example, although we detected statistically significant differences between current smokers and never smokers on measures of pain severity and pain interference, the clinical significance of these results remains unclear. Future research would benefit from longitudinally investigating the temporal relation between pain, smoking, and quitting smoking among persons with cancer in naturalistic settings, perhaps using ecological momentary assessment [28
A second limitation of the current study was that we did not explore mechanistic factors that may underlie the relation between pain and current smoking among persons diagnosed with cancer. Understanding the influence of emotional, physical, and cognitive factors associated with persistent smoking could better inform the development of smoking cessation and relapse-prevention interventions for this population. Given the potential adverse effects of continued smoking on cancer treatment and outcome (e.g., [15
]), additional research is clearly warranted.
A third limitation is that these results are not necessarily generalizable to all persons with cancer. For example, 88% of participants in the current study were Caucasian, 74% had already undergone surgery, and this study excluded patients with poor performance statuses. Thus, it is unclear to what extent these findings may be applicable to patients of varied race and ethnicity, those diagnosed at earlier disease stages, and those with greater functional limitations. It should also be noted that our sample of current smokers was relatively small (n = 36), and the extent to which this is representative of all persons with cancer remains unclear. To extend the current findings, future cross-sectional studies into the association between pain and smoking will require larger, more diverse populations of cancer patients.
In summary, the current data indicated that continued smoking despite a cancer diagnosis was associated with increased pain and increased interference from pain, after controlling for age, gender, surgery status, disease stage, and education. A negative correlation between pain ratings and number of years since quitting smoking was also observed. Finally, these findings were obtained among a sample of patients with a range of cancer diagnoses.