|Year : 2019 | Volume
| Issue : 5 | Page : 1109-1113
Factors that affect the presence of the entire liver incidentally detected by the simulation computed tomography and the detection of inferior border through anthropometric measurement in breast cancer patients
Department of Radiation Oncology, Institute of Oncology, Istanbul University, Istanbul, Turkey
|Date of Web Publication||4-Oct-2019|
Department of Radiation Oncology, Institute of Oncology, Istanbul University, Millet Caddesi 34093 Capa-Fatih, Istanbul
Source of Support: None, Conflict of Interest: None
Objective: The aim was to evaluate the parameters that influence the incidental presence of whole liver detected by simulation computed tomography (simCT) while irradiation in breast cancer patients and to evaluate the factors predicting the presence of the liver in simCT scanning and defining the inferior border in simCT.
Subjects and Methods: We analyzed simCT radiotherapy (RT) planning images of 327 patients with breast cancer. During the evaluation, whether the entire liver was included in the simCT scanning and the level of the vertebra where the inferior border of the simCT scan passed were investigated. Left (L) and right (R) lung, L and R breast, and heart volume were recorded so that they would reflect the internal volume of the thorax. From the simCT images, anteroposterior (A-P) distance at the jugular notch level, A-P and R-L lateral distances at manubriosternal joint alignment, A-P and R-L lateral distances at xiphisternal joint alignment were measured. The predictive value of these measurements and volumes on whether the liver was present in simCT were determined by receiver operating characteristic (ROC) curve analysis.
Results: The liver was included in 72 (22%) out of 327 simCT scans. ROC analysis was applied to the whole group; bilateral lung volume (P < 0.001), bilateral lung + heart volume (P < 0.001), xiphisternal angle R-L lateral distance (P = 0.009), manubriosternal angle A-P distance (P = 0.49), R breast volume (P = 0.007), and L breast volume (P < 0.001) were associated with the visualization of liver. A total of 37 of 72 patients, whose inferior level of the simCT sections passed below L1, had entire liver visualization. The cutoff value of xiphisternal joint R-L lateral distance was found as 31.55 cm, and its sensitivity and specificity were calculated as 81%, and 60%, respectively.
Conclusion: Through R-L lateral measurement taken from the midaxillary line at the level of the xiphisternal joint, we showed that liver would be present in simCT with a sensitivity of 81% at L1 level in those 31.55 cm and above.
Keywords: Breast cancer, liver, radiation therapy, radiation-induced liver toxicity
|How to cite this article:|
Ibis K. Factors that affect the presence of the entire liver incidentally detected by the simulation computed tomography and the detection of inferior border through anthropometric measurement in breast cancer patients. J Can Res Ther 2019;15:1109-13
|How to cite this URL:|
Ibis K. Factors that affect the presence of the entire liver incidentally detected by the simulation computed tomography and the detection of inferior border through anthropometric measurement in breast cancer patients. J Can Res Ther [serial online] 2019 [cited 2019 Nov 13];15:1109-13. Available from: http://www.cancerjournal.net/text.asp?2019/15/5/1109/244449
| > Introduction|| |
Breast cancer is the most common malignancy in women. Radiotherapy (RT) provides clinical benefits in patients with breast-conserving therapy and for patients after radical mastectomy with risk factors. In breast RT, when applying simulation computed tomography (simCT), it is usually aimed that the upper level should pass 5 cm above the cricoid cartilage, while the lower level should include the breast volume and the lungs in simCT. In some patients, the liver receives more doses than expected due to anatomical differences. In order to assess this, the entire liver must be included in the simCT scan. The aim of this study was to evaluate the parameters affecting the detection of incidental presence of the entire liver in simulation scanning and determine the preferred inferior border of simCT.
| > Subjects and Methods|| |
The simCT images in the planning system of 327 patients with breast cancer were examined at the Institute of Oncology, Istanbul University, Turkey. In the assessment, whether the whole liver was included in simCT was determined, and the vertebral level at the inferior border of the simCT scan was noted. Right (R) lung, left (L) lung, and heart volumes were recorded to reflect the internal thoracic volume. The R and L breast volumes were also measured because they could increase the RT treatment volume and drop the inferior border of the simCT. The appropriate breast volume variable was created with the opposite breast volume in patients with previous mastectomy. Considering the anthropometric measurements could provide information about status of the presence of the liver in simCT, some distances between various anatomical points can be measured with the help of a caliper. These distances between the anatomical landmarks were determined as anteroposterior (A-P) distance at the jugular notch level, the A-P distance, and R-L lateral distance at the level of manubriosternal joint, and the A-P distance, and R-L lateral distance at the level of the xiphisternal joint [Figure 1] and [Figure 2]. The predictive effect of these anthropometric measurement and organ volume determination on the presence of whole liver in simCT were evaluated by receiver operating characteristic (ROC) curve analysis. Analyses were performed with SPSS software version 20 (SPSS IBM Corp., Armonk, NY, USA). P < 0.05 was determined as statistically significant.
|Figure 1: Axial, sagittal, and coronal simulation computed tomography scans in right-sided breast cancer. (a) Blue arrow: Relation between the right breast volume and the liver. Red arrow: Whole liver is in the image (b) Blue arrow: Right breast volume and the liver. Green arrow: A part of the liver is in the image|
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|Figure 2: Anthropometric measurement model at xiphisternal joint level in axial, sagittal, and coronal simulation computed tomography scans. (A) Xiphisternal joint (B) Anteroposterior distance measurement (C) Midaxillary line right–left lateral distance measurement|
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| > Results|| |
A total of 169 (51.7%) out of 327 patients had R breast cancer and 158 (48.3%) patients had L breast cancer. The whole liver was scanned in 72 (22%) patients via simCT. Median R breast volume was found as 617 cm 3, median L breast volume as 648.7 cm 3, median R lung volume as 1400 cm 3, median L lung volume as 1119 cm 3, median heart volume as 490.6 cm 3, median bilateral lung + heart volume as 3061.7 cm 3, median jugular notch A-P distance as 16.9 cm, median manubriosternal angle A-P distance as 20 cm, median manubriosternal angle R-L lateral distance as 31.5 cm, median xiphisternal angle A-P distance as 22.3 cm, and median xiphisternal angle R-L lateral distance as 32.3 cm [Table 1].
|Table 1: Measurements in whole groups with simulation computed tomography|
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After examining the inferior border of the simCT scanning, we found that inferior border was below T11 in 73 (22.3%), below T12 in 154 (47.1%), below L1 in 72 (22%), below L2 in 26 (8%), and below L3 in 2 (0.6%) patients. Whole liver was present in 2 (2.7%) of 73 patients whose lower limit passed under T11 (vertebra), in 12 (7.8%) of 154 patients whose lower limit passed under T12, in 37 (51.4%) of 72 patients whose lower limit passed under L1, in 19 (73.1%) of 26 patients whose lower limit passed under L2, and in 2 (0.6%) of 2 patients (100%) whose lower limit passed under L3 vertebral level. Whole liver could be imaged only in 14 out of 227 patients with a lower border below T11 and/or T12 [Table 2].
|Table 2: Simulation computed tomography lower level and inclusion of whole liver|
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The whole group was evaluated by ROC analysis. In simCT imaging, the inferior border was found to be different among patients (e.g., T11, T12, and L1). In order to eliminate these effects, the subgroup, which contains patients whose inferior border is under L1, was also analyzed by ROC. There were 72 patients in the group representing below L1, in half of which, liver was included in simCT. For the whole group, as bilateral lung volume + heart volume (P < 0.001), bilateral lung volume (P < 0.001), R lung volume (P < 0.001), and L lung volume (P < 0.001) increased, the entire liver was less likely to be visualized. As the R breast volume (P = 0.007) and the L breast volume (P < 0.001) increased, the probability of visualizing the entire liver increased. As manubriosternal angle A-P distance (P = 0.049) and xiphisternal R-L lateral distance (P = 0.009) increased, the likelihood of visualizing the complete liver increased [Table 3]. For images where the simCT inferior border passed below the L1, as bilateral lung volume + heart volume (P < 0.001), bilateral lung volume (P < 0.001), R lung volume (P < 0.001), and L lung volume (P < 0.001) increased, the entire liver became less likely to be visible. There was no relationship with the heart volume (P = 679). As the L breast volume (P = 0.001) and the appropriate breast volume (P = 0.006) increased, the entire liver was more likely to be visualized, but there was no correlation with the R breast volume (P = 0.061). As manubriosternal angle A-P distance (P = 0.010), manubriosternal angle R-L lateral distance (P = 0.031), xiphisternal A-P distance (P = 0.035), and xiphisternal R-L lateral distance (P = 0.001) increased, there was a possibility that the entire liver was likely to be visualized [Table 4]. The cutoff value, sensitivity, and specificity of xiphisternal joint were examined, which were found to be 31.55 cm, 81%, and 60% [Table 5]. Considering the whole group, the cutoff value for manubriosternal angle A-P distance was 20 cm and those representing manubriosternal angle A-P distance of 20 cm and above had 61% sensitivity and 54% specificity, which allow the entire liver to be visualized. The cutoff value for the R-L lateral distance of the xiphisternal joint was 31.65 cm. Patients with a R-L lateral distance of the xiphisternal joint being 31.65 cm and above had 71% sensitivity and 49% specificity, and so the entire liver was visualized. In the images where the lower limit L1 passed below L1 vertebra, the cutoff value of manubriosternal angle for the A-P distance was 20 cm and those with the manubriosternal angle of 20 cm and above had 73% sensitivity and 63% specificity, which allow the entire liver to be visualized. The cutoff value of R-L lateral distance was 31.95 cm and those with manubriosternal angle R-L lateral distance of 20 cm and above had 62% sensitivity and 57% specificity, which allow the entire liver to be visualized. The cutoff value of the A-P distance of the xiphisternal joint was 22.25 cm. Those with an A-P distance of 22.25 cm and above had 73% sensitivity and 54.3% specificity, which allow the entire liver to be visualized. The cutoff value of the R-L lateral distance of the xiphisternal joint was 31.55 cm. Those with xiphisternal joint R-L lateral distance of 31.55 cm and above had 81% sensitivity and 60% specificity, which allow the entire liver to be visualized.
|Table 3: Receiver operating characteristic analysis results of the entire study population|
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|Table 4: Receiver operating characteristic analysis results of patients with simulation computed tomography lower level below L1 vertebra|
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|Table 5: Cutoff values, sensitivity, and specificity according to receiver operating characteristic analysis|
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| > Discussion|| |
RT affects both tumor cells and normal tissue. It may be problematic to interpret liver function tests during a follow-up period of RT applied for lower thoracic and abdominal cancers. Transient post-RT changes and decreased radiographic liver density were reported frequently, with elevated liver function tests, in the incidental irradiated liver. Radiation-associated liver toxicity can be recognized, but its relation with breast RT has not been well studied.
Khozouz et al. observed locoregional recurrence in a patient with breast cancer, during breast-conserving surgery, and chemotherapy after axillary dissection. Bilateral mastectomy and 60 Gy RT to the R chest wall were applied. After 6 weeks of irradiation, they found elevated alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase levels during follow-up. Abdominal CT revealed an abnormal visualization showing radiation-induced liver disease (RILD) in the liver area exposed to radiation. RILD occurs in 4–8 weeks after radiation exposure.,,, The symptomatic RILD develops in 6%–66% of patients exposed to radiation over 30–35 Gy depending on the irradiated liver volume and hepatic function. Ascites and hepatomegaly may develop in patients with elevated liver enzymes after liver irradiation.,, Most patients recover completely within 3 to 5 months, but it may progress to fibrosis and liver failure., Hormati et al. established three groups of twenty cases in their study evaluating the prevalence of liver fibrosis and steatohepatitis in breast cancer patients receiving RT. These groups consisted of those with RT, without RT, and with RT for R and L breast cancer. Although the liver and breast were anatomically adjacent, they reported that they did not find any significant correlation between breast cancer RT and liver fibrosis. However, the number of patients in this study group is limited. Due to anatomical differences, the possibility of radiation exposure of the liver with a significant irradiation is variable. Our institutional unpublished data about irradiated breast cancer patients revealed that >40% of the liver received a dose of 10 Gy and above in 13.3% out of 113 patients. In other words, patients who are not selected may not be manifested clinically because of the possibility of receiving lower doses by the liver.
In the present study, I aimed to find the possibility of inclusion of whole liver, which is usually not considered as an organ at risk in breast cancer RT, into the simCT through determining the right lower scanning level. Although it is now easy to incorporate liver into simCT, my analysis showed how differences in body structure may affect whether the liver is visualized or not. It could be stated that liver will be visualized in simCT if the breast volume is greater, the xiphisternal joint R-L lateral distance is 31.55 cm and above, and the cross-sectional image passes under L1 vertebra with 81% sensitivity and 60% specificity.
| > Conclusion|| |
Nowadays, intensity-modulated radiation therapy is used more frequently in RT for breast cancer. Therefore, the amount of liver exposed to low doses is increased. It is important to contour the entire organ to evaluate the received irradiation dose of the liver. In this study, we showed that the possibility of liver visualization in simCT increases with higher R and L breast volumes, longer xiphisternal joint R-L lateral distance, and lower lung volumes. In RT of right-sided breast cancer, the radiation dose received by the liver should be kept in mind. The upper border of simCT should be placed 5 cm above the cricoid cartilage and the lower border should be placed at least below L1 vertebra in patients with a xiphisternal joint R-L lateral distance 31.55 cm and above in order to scan the entire liver.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]