Diagnostic Pathology - Latest Comments

Cell free DNA and methylation patterns described as a possible result of smoking frequency.

Henry Beevers — 2013-01-03T20:10:48Z

Due to the use of an entirely smoker free 'healthy' control group (CTR), this paper fails to distinguish between cell free DNA and methylation patterns caused by smoking, COPD and lung cancer. The increases seen in cell free DNA and increased promoter methylation of CDKN2A and MGMT could be caused by smoking as both the COPD and lung cancer groups in the study are entirely made up of smokers whilst being compared with a healthy group of non smokers, showing reduced cell free DNA and promoter region methylation.

Either non-smoker COPD and lung cancer subjects or smoking 'healthy' subjects should have been included in order to remove the possibility that any differentiation between the groups is a direct cause of smoking which the current set of results fails to do. A possible mechanism for smoking as the cause for methylation pattern differences is shown by the authors themselves in figure 1. which shows a proposed mechanism by which tobacco NNK results in guanosine methylation.

In addition, figure 2. has clearly been mislabeled with 'CRT' and 'EPOC as two of the groups where it should read 'CTR' and 'COPD'.

Author's correction

Tomasz K Wojdacz — 2013-01-03T20:10:25Z

In the paper we wrote:
"The study by Wong et al. [2] involved 12 breast cancer patients paired tumor and PB DNA samples. The authors in this study reported generally low levels of methylation detected in PB (for most of the samples less than 5%) and furthermore, three patients with BRCA1 methylation in PB DNA did not display BRCA1 methylation in the paired tumor sample."

The correct version of this sentence should read:
"The study by Wong et al. [2] involved 9 breast cancer patients with tumor and paired PB DNA samples displaying methylation of the BRCA1 gene. The authors in this study reported generally low levels of methylation detected in PB (for most of the samples less than 5%) and furthermore, one patient with BRCA1 methylation in PB DNA did not display BRCA1 methylation in the paired tumor sample and for one patient the methylation in tumor DNA could not be confirmed by secondary method used in the experiment."

We sincerely apologize the authors of the quoted paper for the mistake

The Authors

Change 1st cousins to 2nd cousins in Table 2.

Latifa Chkioua — 2012-01-05T11:56:34Z

I comet a mistake, I will like to correct it.
I will like to correct this mistake. These patients were offspring of consanguineous marriage of second degree. The parents of this family have the same grandfather with different wife.

Typographical error

Hongxiu Han — 2012-01-05T11:41:20Z

The data 97.2% shown in the article should be 96.9%. We apologize for the oversight.

On number of sections and statistical power

Vincenzo Della Mea — 2009-02-10T09:18:10Z

After having attended the Authors' congress presentation, I read the paper with much interest, because it depicts very well a protocol for obtaining reliable results from image analysis on histological sections.

However I would like to point out that the section entitled "Number of sections has little influence on statistical power of the study" reports a result well known since many years: statistical accuracy of a study depends more on the number of subjects enrolled than on the number of samples within the same subject, according to the Gundersen expression “Do more less well” (1). When dealing with rare condition, taking more samples from few subjects seems a shortcut for obtaining statistically significant results, but is not always the case.

(1) Gundersen HJG, Osterby R. Optimizing sampling efficiency of stereological studies in biology: or “do more less well!”. J Microsc 1981; 121-65.