Ann Thorac Surg 2006;81:419-420
© 2006 The Society of Thoracic Surgeons
Original article: General thoracic
Invited commentary
Kemp Kernstine, MD, PhD
Lung Tumor Program, City of Hope National Medical Center, 1500 E Duarte Rd, Warsaw MOB, Duarte, CA 91010
(Email: kkernstine{at}coh.org).
Anatomical resection is the standard treatment for early stage nonsmall cell lung cancer. As radiographic scanning methods are improving and we are identifying cancers at smaller sizes than previously recognized, the issue of limited resection for small peripheral cancers is being reinvestigated. Should small size on computed tomography (CT) be the only criteria with which to determine the type of resection (ie, anatomical versus limited [wedge]) to be performed? The answer would be no, according to the article by Suzuki and colleagues [1]. This study is a retrospective review of a single institutional experience in 349 chemotherapy–radiotherapy naive patients with small, single peripheral lung primary adenocarcinomas during a 4-year period of time from 1999 to 2003 to evaluate a new radiographic classification that may assist in the future management of patients. From their classification, in essence a radiologic Noguchi classification [2], they were able to identify a group of patients who might be best treated with limited resection. In their series, the 42 patients with either N1 or N2 disease seemed to have a greater solid component and less ground glass opacification (GGO) features than those who did not have those features. The authors concluded that their classification may be a useful evaluation system for future trials.
Some articles raise more questions than answers, as does this article. Clinicians should not be tempted to follow the authors' implications (given the retrospective design of this study) that thin-section CT peripheral lung primary adenocarcinomas with pure GGO could possibly be treated with limited resection rather than a lobectomy or a pneumonectomy.
Numerous questions must be answered, to name a few:
- 1 What is the biological significance of CT maximum size? Why 2 cm rather than 3 cm, or possibly 1 cm? Smaller lesions seemed to be less likely malignant, and if malignant, seemed to be less aggressive than their larger counterparts.
- 2 On CT, how accurately is the size among the different types of lesions measured (ie, solid vs GGO vs halo)?
- 3 If size is so important, should it be measured digitally or by visual technique?
- 4 Should CT thin-sections be performed using 1 mm or 2 mm slices?
- 5 Is this new radiographic-appearance classification a true representation of the different biological character of the individual patient's disease or possibly just the authors' estimation of the biological activity? Can it be further improved by a larger study?
- 6 What is the degree of variability in size measurement? Does it differ on CT, or CT software, within or across the numbers of patients, or does it possibly differ when contrast is used?
- 7 Tumor volume has not been helpful in the past. Perhaps with newer software techniques and thinner cuts on CT, volume may be a better estimation of the biological nature of these tumors and result in a greater reliability in the prediction of nodal disease.
- 8 What is the definition of peripheral? If a tumor involves the visceral pleura on CT, and thus a peripheral lesion, the current belief is that it increases the likelihood for nodal disease, and local and systemic recurrence. Some lesions appear adjacent to a fissure yet a distance away from the hilum. Are these peripheral?
- 9 Is the data derived from this single institution generalizable to other institutions and to other countries?
- 10 The Japanese do not routinely use positron emission tomography. Where does PET fit into this overall schema?
- 11 With the explosion of research being performed on tissue and peripheral biomarkers as well as tumor genotype and phenotype, is there additional information that can be provided from them?
Suzuki and colleagues [3] have previously attempted to evaluate small peripheral adenocarcinomas and identify features in them that would help direct treatment [2]. They found that in their series a fibrotic component that was 5 mm or less in size had a significantly better prognosis (ie, 100% 5-year survival) than those patients with a larger fibrotic component. In this article the authors attempt to use the information that they and others had discovered that certain radiologic features in small peripheral lung nodules may confer better prognosis, allowing the selection of patients for possible limited, nonanatomical resection, or even continued follow-up.
In November of 2004, a panel of pathology and radiology experts met in New York to develop a consensus statement concerning the use of radiologic and pathologic data and treatment options for less malignant lung cancers [4]. Although, in their review of the literature to date, there was insufficient information to recommend any changes to the current treatment recommendations using radiographic findings. One thing they did agree upon, cytology, core needle biopsy, or incisional biopsy did not provide sufficient information to exclude an invasive component in the tumor, an agreed upon poor prognostic pathologic finding. Thus a complete resection of any mass and a thorough pathologic assessment should be performed rather than a biopsy to determine the best means to manage a peripheral GGO lesion. In addition, not all radiographic GGO lesions were found to BAC histologically. Many have equated the two. Those with adenocarcinomas that had initially presented as GGO develop a solid component of 17% and increase in size by 75% [5]. Some will even decrease in size and develop a greater solid component [6]. Dependent upon the population studied, more than 50% of pure GGO lesions will have an invasive component.
Simply, this article does not give us sufficient information to recommend to our referring doctors and their patients that patients with Suzuki type 1 to 4 lesions should undergo limited resection. A carefully designed prospective trial with clear definitions will need to be conducted before we can recommend any changes to be made to current treatment recommendations.
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References
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- Suzuki K, Kusumoto M, Watanabe S, Tsuchiya R, Asamura H. Radiologic classification of small adenocarcinoma of the lungradiologic-pathologic correlation and its prognostic impact. Ann Thorac Surg 2006;81:413-420.[Abstract/Free Full Text]
- Noguchi M, Morikawa A, Kawasaki M, et al. Small adenocarcinoma of the lung. Histologic characteristics and prognosis Cancer 1995;75:2844-2852.[Medline]
- Suzuki K, Yokose T, Yoshida J, et al. Prognostic significance of the size of central fibrosis and peripheral adenocarcinoma of the lung Ann Thorac Surg 2000;69:893-897.[Abstract/Free Full Text]
- Travis WD, Garg K, Franklin WA, et al. Evolving concepts in the pathology and computed tomography imaging of lung adenocarcinoma and bronchioloalveolar carcinoma J Clin Oncol 2004;23:3279-3287.
- Takashima S, Maruyama Y, Hasegawa M, et al. CT findings and progression of small peripheral lung neoplasms have a replacement growth pattern AJR AM J Roentgenol 2003;180:817-826.[Abstract/Free Full Text]
- Kakinuma R, Ohmatsu H, Kaneko M, et al. Progression of focal pure ground-glass opacity detected by low-dose helical computed tomography screening for lung cancer J Comput Assist Tomogr 2004;28:17-23.[Medline]
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