{'fraction_non_alphanumeric': 0.023159350155547875, 'fraction_numerical': 0.0076045627376425855, 'mean_word_length': 4.8582995951417, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Preoperative Staging CT Thorax in Patients With Colorectal Cancer: Its Clinical Importance.

To the Editor—in response to hogan et al, we compliment them on their retrospective observational study in relation to the role of preoperative staging Ct thorax in patients with colorectal cancer. the study population is well representative of the united Kingdom and ireland. any attempt to decrease the burden of unnecessary imaging, reducing exposure to ionizing radiation, and prevention of radiation-induced complications must be commended. the article has proposed an interesting point that the staging Ct thorax may be reserved for high-risk patients (node positive and t3/t4 disease), and it may not be mandated in low-risk patients. the association of Coloproctology of Great Britain and ireland guidelines propose to include the preoperative staging of chest with Ct scan unless it will not affect the overall management of the patient. furthermore, they explain the role of the chest x-ray in colorectal cancers and propose that it can be used in patients with no liver metastasis. this article has revealed that only one third of the lung lesions were visible on x-ray in comparison with Ct, which clearly limits its use in the early detection of lung metastasis. this is because lung lesions are small and not detectable on x-ray. another interesting finding addressed in this article was the notable number of incidents of lung metastasis without liver metastasis both in colon and rectal cancers. this certainly limits the role of the x-ray even further in contrast to association of Coloproctology of Great Britain and ireland guidelines. the majority of patients in this study included those with t3/t4 tumors in comparison with t1/t2 tumors (fig. 1 in hogan et al), and the data support the fact that t3/t4 tumors with lymphovascular invasion and lymph node metastasis possess a higher chance of liver and lung metastases. this, however, does not conclude that t1/t2 tumors did not result in pulmonary metastasis and that, therefore, staging Cts were unnecessary in these patients. in a recent article regarding the surgical resection of pulmonary metastasis, 39 of 156 patients had Dukes a/B primary colorectal cancer. therefore, we believe that it may not be safe for preoperative staging Ct thorax to be excluded in low-risk patients. it would be interesting to know the true prevalence of pulmonary metastasis in t1/ t2 cancers without lymph node metastasis and lymphovascular invasion. this may be the first step to determine the routine staging of the chest in colorectal cancers. finally, there may be a typographic error in the Conclusion section of the article, because the authors stated highrisk tumors (node positive, t2/t3) in contrary to the rest of the article (Results and Discussion sections), and we presume that they meant high-risk tumors (node positive, t3/t4).