It is applicable to both men and women independently. CXI is calculated using objective observations and is not limited by recall bias as would be possible if the degree of weight loss was used as the sole measure of cancer cachexia. Another limitation of using only weight loss as a definition of cancer cachexia is that weight loss can vary during a patient’s clinical course; it can be affected by cancer treatment and factors that may mask true weight loss such as fluid retention.
Lung cancer is the leading cause of cancer-related mortality in the United States. Even stage-to-stage survival for lung cancer is worse than other common cancer types such as colorectal, prostate, and breast.1 One of the possible reasons for such poor outcome can be development of cancer cachexia in patients with advanced lung cancer.
Many patients with advanced NSCLC lose weight, have a poor PS, and are unable to receive cancer chemotherapy. Most of the focus of lung cancer research has been on targeting proliferating cancer cells either through cytotoxic chemotherapy, targeted agents, or, more recently, immunotherapy. Very little focus has been laid on developing therapies that target systemic inflammation or cancer cachexia in the context of managing advanced lung cancer patients.
Hopefully, this will change with inclusion of cachexia in the provocative question initiative by the NCI. Another thing to consider will be to identify if the presence of certain mutations makes a patient more prone to develop cancer cachexia, and hence, poor outcome, for example, presence of K-ras as opposed to EGFR. Currently, there is paucity of literature in this regard.
This study has several limitations. It is a retrospective chart review, and many patients were excluded due to insufficient information. CXI as such does not tell us if the patient has cachexia or not, but it does categorize the patient into low risk and high risk based on clinical variables known to be associated with cancer cachexia. Because CXI is a continuous variable, there may be little difference in clinical course of someone with CXI of 37 and 34 though they fall into stage I and stage II cachexia, respectively.
Additionally, although the CXI is easy to calculate, it may be difficult to measure in routine clinical practice, thus limiting its applicability to research settings only. It can, however, be very useful identifying high-risk patients who take part in cachexia intervention studies stratifying them into good risk and poor risk.
Despite these limitations, the CXI is an objective method of estimating the degree of cancer cachexia in patients with advanced NSCLC. It can thus be used to identify patients who are at high risk of early progression and less likely to receive cancer treatment.
It can also be used to identify which patients should be treated with therapies directed against cancer cachexia. The CXI should be validated in larger prospective studies of both early- and advanced-stage NSCLC and other cancers.
Syed Husan Raza Jafri1, Carlos Previgilano2, Keerti Khandelwal2, and Runhua Shi2
1University of Texas Health Science Center, Houston, TX, USA. 2Louisiana State University Health Science Center, Shreveport, LA, USA.
Conceived and designed the experiments: SHRJ. Analyzed the data: SHRJ, CP, KK, RS. Wrote the first draft of the manuscript: SHRJ. Contributed to the writing of the manuscript: SHRJ, CP, KK, RS. Agree with manuscript results and conclusions: SHRJ, CP, KK, RS. Jointly developed the structure and arguments for the paper: SHRJ, CP, RS. Made critical revisions and approved final version: SHRJ, RS, CP. All authors reviewed and approved of the final manuscript.