letter to the editor

Cancer after kidney transplant To the Editor: The recent article by Farrugia et al.1 appears to advocate surveillance for cancer after kidney transplant, which implies screening. However, screening for cancer does not benefit patients with a kidney transplant.2 Consider the three most common cancers in this article: lymphoma, lung, and kidney. One cannot screen for lymphoma because it is too variable in its presentation. The death rate for lung cancer in the UK general population is 60 per 100,000, which is the same as the death rate for lung cancer in the Farrugia et al.1 cohort. Lung cancer is thus not increased in kidney transplant patients. The utility for screening for lung cancer in the general population is controversial.3 As for kidney cancer, screening for kidney cancer in kidney transplant patients is not cost-effective.4 Vigilance for symptoms and better cancer treatment will save lives, not surveillance programs. 1.

2.

3. 4.

Farrugia D, Mahboob S, Cheshire J et al. Malignancy-related mortality following kidney transplantation is common. Kidney Int 2014; 85: 1395–1403. Kiberd BA, Keough-Ryan T, Clase CM. Screening for prostate, breast, and colorectal cancer in renal transplant recipients. Am J Transplant 2003; 3: 619–625. Manser R, Lethaby A, Irving LB et al. Screening for lung cancer. Cochrane Database Syst Rev 2013; 6: CD001991. Wong G, Howard K, Webster AC et al. Screening for renal cancer in recipients of kidney transplants. Nephrol Dial Transplant 2011; 26: 1729–1739.

cancer or acquired cystic change and subsequent malignant transformation in native kidneys owing to prolonged time on dialysis before transplantation (while awaiting appropriate cancer-free intervals). Either scenario identifies a high-risk group that may warrant targeted screening (and could be cost-effective owing to small numbers), although further work would be required to determine what equates to ‘prolonged’ time on dialysis. Finally, by suggesting heightened surveillance we are not implying screening as the best strategy. The word surveillance incidentally comes from the French phrase for ‘watching over’ (‘sur’ meaning ‘from above’ and ‘veiller’ meaning ‘to watch’). In this respect, it is clear that Dr Cohen and we are actually advocating a very similar approach of watching over our patients. 1. 2.

Cohen E. Cancer after kidney transplant. Kidney Int 2014; 86: 1271. Farrugia D, Mahboob S, Cheshire J et al. Malignancy-related mortality following kidney transplantation is common. Kidney Int 2014; 85: 1395–1403.

Adnan Sharif1 1 Department of Nephrology and Transplantation, Queen Elizabeth Hospital, Birmingham, UK Correspondence: Adnan Sharif, Department of Nephrology and Transplantation, Queen Elizabeth Hospital, Edgbaston, Birmingham B15 2WB, UK. E-mail: [email protected]

Kidney International (2014) 86, 1271; doi:10.1038/ki.2014.289

Eric P. Cohen1,2 1

Kidney International (2014) 86, 1271; doi:10.1038/ki.2014.288

Dapagliflozin does not show improvement in glycemic control in moderate renal impairment: a question of analytical rigor?

The Author Replies: We appreciate the interest from Dr Cohen1 regarding our recent article.2 Reflecting upon the increasing burden of malignancy-related mortality post kidney transplantation, Dr Cohen suggests that increased vigilance and treatment (rather than screening) is the best strategy to save lives. We agree that the most common malignancy-related deaths identified in our analysis (lymphoma, lung, and renal) have unproven merits as screening strategies. Indeed, we specifically highlight that ‘effective screening strategies after transplantation lack validation for efficacy’.2 However, we do suggest further work to explore the merit of screening for posttransplant renal cancer. This is due to renal cancer accounting for over half of malignancy-related deaths post kidney transplantation in recipients with pretransplant cancer. This may reflect pretransplant history of renal

To the Editor: We read with great interest the remarkable randomized controlled trial by Kohan et al.1 The authors set out to investigate the effects of dapagliflozin in patients with moderate renal impairment.1 Reductions in both weight and blood pressure were observed, but no significant improvement in glycemic control was observed, as monitored using HbA1c.1 Excellence in performance and reporting of clinical trials is vital and is promoted by initiatives such as SPIRIT. However, the SPIRIT checklist lacks rigor with regards to laboratory methods and only requires documentation of ‘a description of study instruments (e.g., questionnaires and laboratory tests) along with their reliability and validity, if known.’2 Assays should ideally be chosen to reduce possible interference and be standardized across sites. High-performance liquid chromatography using ion exchange to separate HbA1c is subjected to interference from carbamylated hemoglobin, addition of isocyanic acid derived from urea, which co-elutes with glycated hemoglobin due to its similar charge.3 Affinity chromatography is not subjected to this interference;3 however, the paper methodology gives

Department of Medicine/Nephrology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA and 2Zablocki VA Medical Center, Milwaukee, Wisconsin, USA Correspondence: Eric P. Cohen, Department of Medicine/Nephrology, Medical College of Wisconsin, 9200 W Wisconsin Avenue, Milwaukee, Wisconsin 53226, USA. E-mail: [email protected]

Kidney International (2014) 86, 1269–1272

1271

Cancer after kidney transplant.

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