Growth rate of pancreatic adenocarcinoma: initial clinical experience

Stretchable ultrasonic arrays for the three-dimensional mapping of the modulus of deep tissue

Serial assessment of the biomechanical properties of tissues can be used to aid the early detection and management of pathophysiological conditions, to track the evolution of lesions and to evaluate the progress of rehabilitation. However, current methods are invasive, can be used only for short-term measurements, or have insufficient penetration depth or spatial resolution. Here we describe a stretchable ultrasonic array for performing serial non-invasive elastographic measurements of tissues up to 4 cm beneath the skin at a spatial resolution of 0.5 mm. The array conforms to human skin and acoustically couples with it, allowing for accurate elastographic imaging, which we validated via magnetic resonance elastography. We used the device to map three-dimensional distributions of the Young's modulus of tissues ex vivo, to detect microstructural damage in the muscles of volunteers before the onset of soreness and to monitor the dynamic recovery process of muscle injuries during physiotherapies. The technology may facilitate the diagnosis and treatment of diseases affecting tissue biomechanics.

Earlier Diagnosis of Pancreatic Cancer: Is It Possible?

Pancreatic ductal adenocarcinoma has a very high mortality rate which has been only minimally improved in the last 30 years. This high mortality is closely related to late diagnosis, which is usually made when the tumor is large and has extensively infiltrated neighboring tissues or distant metastases are already present. This is a paradoxical situation for a tumor that requires nearly 15 years to develop since the first founding mutation. Response to chemotherapy under such late circumstances is poor, resistance is frequent, and prolongation of survival is almost negligible. Early surgery has been, and still is, the only approach with a slightly better outcome. Unfortunately, the relapse percentage after surgery is still very high. In fact, early surgery clearly requires early diagnosis. Despite all the advances in diagnostic methods, the available tools for improving these results are scarce. Serum tumor markers permit a late diagnosis, but their contribution to an improved therapeutic result is very limited. On the other hand, effective screening methods for high-risk populations have not been fully developed as yet. This paper discusses the difficulties of early diagnosis, evaluates whether the available diagnostic tools are adequate, and proposes some simple and not-so-simple measures to improve it.

Pancreatic cancer detection with a non-contrast MR protocol: is it reliable?

PURPOSE

The pancreatic cancer (PC) is the 4th leading cancer-related death, becoming the second one by 2030, with a 5 year survival rate of 8%. Considering its increased incidence in high-risk categories compared to the general population, we aimed to validate a non-contrast MR protocol, to detect PC in its earliest phase, which could be suitable as a screening tool in high-risk patients.

MATERIALS AND METHODS

In this retrospective study, we selected 200 patients (> 40 years) from our radiological database, which performed upper abdominal MRI between 2012 and 2017. 100 were negative for pancreatic lesions and 100 positive for pancreatic lesion (< 30 mm). The latter group included: 40 PDAC (pancreatic adenocarcinoma), 42 BD-IPMN (Branch Duct- Intraductal Papillary Mucinous Neoplasm), 10 PNET(pancreatic neuroendocrine tumor), 4 SCN(serous cystic neoplasm), 3 IPS(intrapancreatic spleen), 1 MCN(mucinous cystic neoplasm). Three readers (R1, R2 and R3) with a high, medium and low experience, respectively, analysed, first, the non-contrast MR sequences (single-shot T2w breath-hold, GE T1w FS, DWI and 2D/3D MRCP), and then the standard MR protocol, independently, randomly and anonymously. Readers identified or excluded the presence of pancreatic lesion, in both reading sessions. These results were compared with the histopathological diagnosis, and then divided into 3 different classes of lesions: all lesions, pancreatic adenocarcinoma and solid lesion. Mcnemar's test was used to compare the results. The inter-observer agreement was determined according to the kappa statistic in both protocols, and then the inter-protocol agreement was calculated.

RESULTS

The non-contrast MR protocol has reached statistical parameters values ranging between 83% in SE (sensitivity) by R3 and 99% in NPV (negative predictive value) by R1. The standard MR protocol has reported slight increasing statistical parameters compared to those of the proposed one. However, there are not significant statistical differences between the both protocols. The proposed non-contrast MR protocol has reported the highest NPVs in the PDAC group detection (R1: 99%, R2: 99%, R3: 98%). In all groups of lesions, the agreement between the two protocols was excellent for each Reader ranging from 96 to 98%.

CONCLUSION

The proposed non-contrast MR protocol showed high PC detection values and a time execution ≤ 20 min. Therefore, it can be proposed as a screening tool in high-risk patients.

Maintaining early diagnosis of pancreatic adenocarcinoma in Japan: Local resilience against COVID-19

BACKGROUND AND AIMS

This study evaluated the impact of the coronavirus disease 2019 (COVID-19) pandemic on pancreatic adenocarcinoma (PA) practice in our region and discussed the effects of our institution's regional collaborative system, the "Early Stage Pancreatic Cancer Diagnosis Project," which was originally unrelated to this study's purpose.

METHODS

We retrospectively investigated 150 patients with PA at Yokohama Rosai Hospital by defining three time periods: before (C0), during the first year (C1), and during the second year (C2) of the COVID-19 pandemic.

RESULTS

Among the three periods (C0, C1, and C2), there were significantly less patients with stage I PA (14.0%, 0%, and 7.4%, p = 0.032) in C1, and significantly more patients with stage III PA (10.0%, 28.3%, and 9.3%, p = 0.014) in C1. The pandemic significantly prolonged the median durations from disease onset to patients' first visits (28, 49, and 14 days, p = 0.012). In contrast, there was no significant difference in the median durations from referral to first visit to our institution (4, 4, and 6 days, p = 0.391).

CONCLUSIONS

The pandemic advanced the stage of PA in our region. Although the pancreatic referral network remained functional during the pandemic, there were delays from disease onset to patients' first visit to healthcare providers, including clinics. While the pandemic caused temporary damage to PA practice, the routine regional collaboration provided by our institution's project allowed for early resilience. A notable limitation is that the impact of the pandemic on PA prognosis was not evaluated.

A Novel Diagnostic Imaging Method for the Early Detection of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, with a survival rate of less than 10% [...].

Time to Neoadjuvant Chemotherapy Initiation Is not Associated With Survival in Pancreatic Cancer

INTRODUCTION

Not all patients with pancreatic adenocarcinoma (PDAC) tolerate multiagent neoadjuvant chemotherapy (NAC). We utilized institutional data and the National Cancer Database (NCDB) to investigate if time from diagnosis to NAC initiation is associated with survival.

METHODS

Patients who received NAC and underwent pancreatectomy at our institution (2010-2021) or within the NCDB (2010-2016) were identified. Time from diagnosis to NAC was grouped: <21, 21-35, and >35 d. Recurrence-free (RFS) and overall survival (OS) was compared.

RESULTS

At our institution, 122 patients received NAC before pancreatectomy (<21 d: n = 36; 21-35 d: n = 61; >35 d: n = 25). Demographics, performance status, and anatomic resectability were similar. There was no difference in RFS (13.3 versus 12.4 versus 11.9 mo) or OS (26.7 versus 25.8 versus 26.1 mo) based on NAC timing. Patients who received FOLFIRINOX had an improvement in RFS (14.4 versus 12.2 versus 6.8 mo, P = 0.05) and OS (39.2 versus 21.4 versus 17.3 mo, P = 0.01) compared to gemcitabine with nab-paclitaxel or other regimens. Within the NCDB, 6713 patients were included (<21 d: n = 2087; 21-35 d: n = 2656; >35 d: n = 1970). There was no difference in OS (21.6 versus 20.9 versus 22.2 mo). Multiagent NAC was associated with improved OS compared to single-agent (22.6 versus 18.8 mo, P < 0.001).

CONCLUSIONS

Delay in NAC initiation for PDAC is not associated with survival. Patient optimization could be considered with the goal of improving tolerance of multiagent chemotherapy.

Identification of distinct slow mode of reversible adaptation of pancreatic ductal adenocarcinoma to the prolonged acidic pH microenvironment

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is the most common pancreatic neoplasm with high metastatic potential and poor clinical outcome. Like other solid tumors, PDAC in the early stages is often asymptomatic, and grows very slowly under a distinct acidic pHe (extracellular pH) microenvironment. However, most previous studies have only reported the fate of cancerous cells upon cursory exposure to acidic pHe conditions. Little is known about how solid tumors-such as the lethal PDAC originating within the pancreatic duct-acinar system that secretes alkaline fluids-evolve to withstand and adapt to the prolonged acidotic microenvironmental stress.

METHODS

Representative PDAC cells were exposed to various biologically relevant periods of extracellular acidity. The time effects of acidic pHe stress were determined with respect to tumor cell proliferation, phenotypic regulation, autophagic control, metabolic plasticity, mitochondrial network dynamics, and metastatic potentials.

RESULTS

Unlike previous short-term analyses, we found that the acidosis-mediated autophagy occurred mainly as an early stress response but not for later adaptation to microenvironmental acidification. Rather, PDAC cells use a distinct and lengthy process of reversible adaptive plasticity centered on the early fast and later slow mitochondrial network dynamics and metabolic adjustment. This regulates their acute responses and chronic adaptations to the acidic pHe microenvironment. A more malignant state with increased migratory and invasive potentials in long-term acidosis-adapted PDAC cells was obtained with key regulatory molecules being closely related to overall patient survival. Finally, the identification of 34 acidic pHe-related genes could be potential targets for the development of diagnosis and treatment against PDAC.

CONCLUSIONS

Our study offers a novel mechanism of early rapid response and late reversible adaptation of PDAC cells to the stress of extracellular acidosis. The presence of this distinctive yet slow mode of machinery fills an important knowledge gap in how solid tumor cells sense, respond, reprogram, and ultimately adapt to the persistent microenvironmental acidification.

Gastrointestinal Cancer Stage at Diagnosis Before and During the COVID-19 Pandemic in Japan

IMPORTANCE

The COVID-19 pandemic has delayed medical consultations, possibly leading to the diagnosis of gastrointestinal cancer at advanced stages.

OBJECTIVE

To evaluate stage at diagnosis among patients with gastrointestinal cancer in Japan before and during the COVID-19 pandemic.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included patients in a hospital-based cancer registry who were diagnosed with gastrointestinal cancer (ie, esophageal, gastric, colorectal, pancreatic, liver, and biliary tract cancers) between January 2016 and December 2020 at 2 tertiary Japanese hospitals.

EXPOSURES

The pre-COVID-19 period was defined as January 2017 to February 2020, and the COVID-19 period was defined as March 2020 to December 2020.

MAIN OUTCOME AND MEASURE

Monthly numbers of patients with newly diagnosed cancer were aggregated, classified by stage, and compared.

RESULTS

The study evaluated 5167 patients, including 4218 patients (2825 [67.0%] men; mean [SD] age, 71.3 [10.9] years) in the pre-COVID-19 period and 949 patients (607 [64.0%] men; mean [SD] age, 71.8 [10.7] years) in the COVID-19 period. Comparing the pre-COVID-19 period with the COVID-19 period, significant decreases were observed in the mean (SD) number of patients with newly diagnosed gastric cancer (30.63 [6.62] patients/month vs 22.40 [5.85] patients/month; -26.87% change; P < .001) and colorectal cancer (41.61 [6.81] patients/month vs 36.00 [6.72] patients/month; -13.47% change; P = .03). Significant decreases were also observed in the mean (SD) number of cases of stage I gastric cancer (21.55 [5.66] cases/month vs 13.90 [5.99] cases/month; -35.51% change; P < .001), stage 0 colorectal cancer (10.58 [3.36] cases/month vs 7.10 [4.10] cases/month; -32.89% change; P = .008), and stage I colorectal cancer (10.16 [3.14] cases/month vs 6.70 [2.91] cases/month; -34.04% change; P = .003). No significant increases were observed for esophageal, gastric, pancreatic, liver, or biliary tract cancers. A significant decrease was observed in the mean (SD) number of cases per month of stage II colorectal cancer (7.42 [3.06] cases/month vs 4.80 [1.75] cases/month; -35.32% change; P = .01); a significant increase was observed for the mean (SD) number of cases per month of stage III colorectal cancer (7.18 [2.85] cases/month vs 12.10 [2.42] cases/month; 68.42% change; P < .001).

CONCLUSIONS AND RELEVANCE

In this cohort study of patients in a hospital-based cancer registry form Japan, significantly fewer patients were diagnosed with stage I gastric and colorectal cancers during the COVID-19 pandemic. Thus, the number of screening-detected cancers might have decreased, and colorectal cancer may have been diagnosed at more advanced stages.

Rapidly Progressing Anaplastic Carcinoma of the Pancreas with Mucoepidermoid Carcinoma: An Autopsy Case Report

A 75-year-old man visited our hospital for the examination of a tumor in the pancreas. Computed tomography showed an 85×85-mm low-density tumor in the pancreas. The tumor was pathologically diagnosed as poorly differentiated carcinoma by endoscopic ultrasound-guided fine-needle aspiration. Although we started chemotherapy, the patient died 84 days after the diagnosis. An autopsy demonstrated a ruptured anaplastic carcinoma with mucoepidermoid carcinoma of the pancreas. Anaplastic carcinoma with mucoepidermoid carcinoma is a very rare histologic subtype of pancreatic carcinoma, so pathological findings are important for predicting the patient's prognosis. Physicians should be aware of this rare but fatal disease.

Weight Loss as an Untapped Early Detection Marker in Pancreatic and Periampullary Cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) has the worst survival of common cancers, partly because there are no reliable early detection tests. Unintentional weight loss (≥ 5% decrease from baseline) has been linked to PDAC, but the frequency and severity of weight loss using objective measures, and its relationship to prognosis, have not been well characterized.

METHODS

We identified 390 patients with PDAC (all stages) and two or more prediagnosis weights in the electronic medical record. Percentage weight loss in the 365 and 180 days preceding diagnosis was calculated. Results were compared with raw weights of age- and sex-matched non-cancer controls (n = 780). Odds ratios for PDAC were calculated using conditional logistic regression. Cox proportional hazards models were used for survival.

RESULTS

Within 1 year of diagnosis, more PDAC patients lost ≥ 5% weight relative to controls (74.9% vs. 11.2%; p < 0.001), with a median weight loss of 14.2 versus 2.9 lbs. The odds ratio for PDAC comparing weight loss within 1 year of 5 to < 10% was 10.30 (p < 0.001) and 77.82 for ≥ 10% (p < 0.001), compared with stable weight. Weight loss prior to diagnosis was also associated with early-stage PDAC. PDAC cases with ≥ 10% prediagnosis weight loss had worse survival compared with stable weights (hazard ratio [HR] 1.60; p = 0.01). Greater prediagnosis weight loss was associated with poor survival after pancreatectomy (5 to < 10% vs. < 5%, HR 2.40, p = 0.03; ≥ 10% vs. < 5%, HR 2.59, p = 0.03).

CONCLUSIONS

Diagnosis of PDAC is preceded by unintentional weight loss in the majority of patients, even at an early stage. Greater prediagnosis weight loss severity is also associated with poor postoperative survival.

Hepatocellular Carcinoma Demonstrates Heterogeneous Growth Patterns in a Multicenter Cohort of Patients With Cirrhosis

BACKGROUND AND AIMS

There are limited data on hepatocellular carcinoma (HCC) growth patterns, particularly in Western cohorts, despite implications for surveillance, prognosis, and treatment. Our study's aim was to quantify tumor doubling time (TDT) and identify correlates associated with indolent and rapid growth.

APPROACH AND RESULTS

We performed a retrospective multicenter cohort study of patients with cirrhosis diagnosed with HCC from 2008 to 2017 at six US and European health systems with two or more contrast-enhanced imaging studies performed ≥ 30 days apart prior to HCC treatment. Radiologists independently measured tumors in three dimensions to calculate TDT and specific growth rate (SGR). We used multivariable ordinal logistic regression to identify factors associated with indolent (TDT > 365 days) and rapid (TDT < 90 days) tumor growth. In the primary cohort (n = 242 patients from four centers), median TDT was 229 days (interquartile range [IQR], 89-627) and median SGR was 0.3% per day (IQR, 0.1%-0.8%). Over one-third (38%) of HCCs had indolent growth, 36.8% intermediate growth, and 25.2% rapid growth. In multivariable analysis, indolent growth was associated with larger tumor diameter (odds ratio [OR], 1.15, 95% confidence interval [CI], 1.03-1.30) and alpha-fetoprotein < 20 ng/mL (OR, 1.90; 95% CI, 1.12-3.21). Indolent growth was more common in nonviral than viral cirrhosis (50.9% versus 32.1%), particularly in patients with T1 HCC (OR, 3.41; 95% CI, 1.08-10.80). Median TDT (169 days; IQR 74-408 days) and SGR (0.4% per day) were similar in an independent cohort (n = 176 patients from two centers).

CONCLUSIONS

In a large Western cohort of patients with HCC, we found heterogeneous tumor growth patterns, with one-fourth exhibiting rapid growth and over one-third having indolent growth. Better understanding different tumor growth patterns may facilitate a precision approach to prognostication and treatment.

Tumor growth kinetics by CA 19-9 in patients with unresectable pancreatic cancer receiving chemotherapy: A retrospective analysis

BACKGROUND

Recently, measures of tumor growth kinetics calculated by carbohydrate antigen 19-9 (CA 19-9) determinations after cytotoxic chemotherapy (CHT) have been reported as effective prognostic indicators in locally-advanced unresectable and metastatic pancreatic adenocarcinoma (mPDAC). The study aims to evaluate the prognostic role of tumor kinetics measured by CA 19-9 in patients with mPDAC, measuring it by three different ways.

METHODS

Patients with mPDAC receiving a first-line CHT between 2009 and 2017 were identified, and those for whom CA 19-9 data were available were enrolled. Three CA 19-9-related variables were calculated: CA 19-9 related reduction rate (RR) and tumor growth rate (G), after 8 weeks of CHT, tumor growth and inflammation index (TGII), after 90 days of CHT. The relationships with the outcome were analysed, and a Cox model has been build with each of the three variables.

RESULTS

Of 118 patients only 48 were eligible for the analysis. RR, G, or TGII appear as significant prognostic factors, and, after multivariate analysis, a reduction rate of 20% the baseline or more was associated with good survival (HR 0.321; CIs 0.156-0.661) as well as a G > -0.4%/day (HR 2.114; CIs 1.034-4.321), whereas TGII >190 was not correlated with the outcome (HR 1.788; CIs 0.789-4.055).

CONCLUSIONS

In patients with mPDAC, after 8 weeks of first-line CHT, CA 19-9-related tumor reduction or growth rate appear as valuable prognostic factors.

Specific Growth Rate as a Predictor of Survival in Pancreatic Neuroendocrine Tumors: A Multi-institutional Study from the United States Neuroendocrine Study Group

BACKGROUND

Pancreatic neuroendocrine tumors (PNETs) are often indolent; however, identifying patients at risk for rapidly progressing variants is critical, particularly for those with small tumors who may be candidates for expectant management. Specific growth rate (SGR) has been predictive of survival in other malignancies but has not been examined in PNETs.

METHODS

A retrospective cohort study of adult patients who underwent PNET resection from 2000 to 2016 was performed utilizing the multi-institutional United States Neuroendocrine Study Group database. Patients with ≥ 2 preoperative cross-sectional imaging studies at least 30 days apart were included in our analysis (N = 288). Patients were grouped as "high SGR" or "low SGR." Demographic and clinical factors were compared between the groups. Kaplan-Meier and log-rank analysis were used for survival analysis. Cox proportional hazard analysis was used to assess the impact of various clinical factors on overall survival (OS).

RESULTS

High SGR was associated with higher T stage at resection, shorter doubling time, and elevated HbA1c (all P ≤ 0.01). Patients with high SGR had significantly decreased 5-year OS (63 vs 80%, P = 0.01) and disease-specific survival (72 vs 91%, P = 0.03) compared to those with low SGR. In patients with small (≤ 2 cm) tumors (N = 106), high SGR predicted lower 5-year OS (79 vs 96%, P = 0.01). On multivariate analysis, high SGR was independently associated with worse OS (hazard ratio 2.67, 95% confidence interval 1.05-6.84, P = 0.04).

CONCLUSION

High SGR is associated with worse survival in PNET patients. Evaluating PNET SGR may enhance clinical decision-making, particularly when weighing expectant management versus surgery in patients with small tumors.

Development of a Physiologically-Based Mathematical Model for Quantifying Nanoparticle Distribution in Tumors

Nanomedicine holds promise for the treatment of cancer, as it enables tumor-targeted drug delivery. However, reports on translation of most nanomedicine strategies to the clinic so far have been less than satisfactory, in part due to insufficient understanding of the effects of nanoparticle (NP) physiochemical properties and physiological variables on their pharmacological behavior. In this paper, we present a multiscale mathematical model to examine the efficacy of NP delivery to solid tumors; as a case example, we apply the model to a clinically detectable primary pancreatic ductal adenocarcinoma (PDAC) to assess tissue-scale spatiotemporal distribution profiles of NPs. We integrate NP systemic disposition kinetics with NP-cell interactions in PDAC abstractly described as a two-dimensional structure, which is then parameterized with human physiological data obtained from published literature. Through model analysis of delivery efficiency, we verify the multiscale approach by showing that NP concentration kinetics of interest in various compartments predicted by the whole-body scale model were in agreement with those obtained from the tissue-scale model. We also found that more NPs were trapped in the outer well-perfused tumor region than the inner semi-necrotic domain. Further development of the model may provide a useful tool for optimal NP design and physiological interventions.

Gastrointestinal Malignancies and the COVID-19 Pandemic: Evidence-Based Triage to Surgery

BACKGROUND

The COVID-19 pandemic has led to widespread cancelation of electively scheduled surgeries, including for colorectal, pancreatic, and gastric cancer. The American College of Surgeons and the Society of Surgical Oncology have released guidelines for triage of these procedures. We seek to synthesize available evidence on delayed resection and oncologic outcomes, while also providing a critical assessment of the released guidelines.

METHODS

A systematic review was conducted to identify literature between 2005 and 2020 investigating the impact of time to surgery on oncologic outcomes in colorectal, pancreatic, and gastric cancer.

RESULTS

For colorectal cancer, 1066 abstracts were screened and 43 papers were included. In primarily resected colon cancer, delay over 30 to 40 days is associated with lower survival. In rectal cancer, time to surgery over 7 to 8 weeks following neoadjuvant therapy is associated with decreased survival. Three hundred ninety-four abstracts were screened for pancreatic cancer and nine studies were included. Two studies demonstrate increased unexpected progression with delayed surgery over 30 days. Out of 633 abstracts screened for gastric cancer, six studies were included. No identified study demonstrated worse survival with increased time to surgery.

CONCLUSION

Moderate evidence suggests that delayed resection of colorectal cancer worsens survival; the impact of time to surgery on gastric and pancreatic cancer outcomes is uncertain. Early resection of gastrointestinal malignancies provides the best chance for curative therapy. During the COVID-19 pandemic, prioritization of procedures should account for available evidence on time to surgery and oncologic outcomes.

Consecutive seeding and transfer of genetic diversity in metastasis

During metastasis, only a fraction of genetic diversity in a primary tumor is passed on to metastases. We calculate this fraction of transferred diversity as a function of the seeding rate between tumors. At one extreme, if a metastasis is seeded by a single cell, then it inherits only the somatic mutations present in the founding cell, so that none of the diversity in the primary tumor is transmitted to the metastasis. In contrast, if a metastasis is seeded by multiple cells, then some genetic diversity in the primary tumor can be transmitted. We study a multitype branching process of metastasis growth that originates from a single cell but over time receives additional cells. We derive a surprisingly simple formula that relates the expected diversity of a metastasis to the diversity in the pool of seeding cells. We calculate the probability that a metastasis is polyclonal. We apply our framework to published datasets for which polyclonality has been previously reported, analyzing 68 ovarian cancer samples, 31 breast cancer samples, and 8 colorectal cancer samples from 15 patients. For these clonally diverse metastases, under typical metastasis growth conditions, we find that 10 to 150 cells seeded each metastasis and left surviving lineages between initial formation and clinical detection.

Tumour-specific and organ-specific protein synthesis rates in patients with pancreatic cancer

BACKGROUND

Living tissues maintain a fine balance between protein synthesis and protein breakdown rates. Animal studies indicate that protein synthesis rates are higher in organs when compared with skeletal muscle tissue. As such, organ and tumour protein synthesis could have major effects on whole-body protein metabolism in wasting disorders such as cancer cachexia. We aimed to assess protein synthesis rates in pancreatic tumour tissue and healthy pancreas, liver, and skeletal muscle tissue in vivo in humans.

METHODS

In eight patients with pancreatic cancer undergoing pancreaticoduodenectomy, primed continuous infusions with L-[ring-¹³ C₆ ]phenylalanine and L-[3,5-² H₂ ]tyrosine were started prior to surgery and continued throughout the surgical procedures. During surgery, plasma samples and biopsies from the pancreas, pancreatic tumour, liver, and vastus lateralis muscle were taken. Post-absorptive fractional protein synthesis rates were determined by measuring incorporation of labelled L-[ring-¹³ C₆ ]phenylalanine in tissue protein using the weighed plasma L-[ring-¹³ C₆ ]phenylalanine enrichments as the precursor pool.

RESULTS

Five male patients and three female patients with a mean age of 67 ± 2 years were included into this study. Plasma L-[ring-¹³ C₆ ]phenylalanine enrichments (6-9 mole per cent excess) did not change during surgery (P = 0.60). Pancreatic tumour protein synthesis rates were 2.6-fold lower than surrounding pancreatic tissue protein synthesis rates (0.268 ± 0.053 vs. 0.694 ± 0.228%/h, respectively; P = 0.028) and 1.7-fold lower than liver protein synthesis rates (0.268 ± 0.053 vs. 0.448 ± 0.043%/h, respectively; P = 0.046). Among healthy organ samples, protein synthesis rates were 20-fold and 13-fold higher in pancreas and liver, respectively, compared with skeletal muscle tissue (0.694 ± 0.228 and 0.448 ± 0.043 vs. 0.035 ± 0.005%/h, respectively; P < 0.05).

CONCLUSIONS

Liver and pancreas tissue protein synthesis rates are higher when compared with pancreatic tumour and skeletal muscle tissue protein synthesis rates and can, therefore, strongly impact whole-body protein metabolism in vivo in humans.

Why is pancreatic cancer so deadly? The pathologist's view

The remarkable aggressiveness of pancreatic cancer has never been fully explained. Although clearly multifactorial, we postulate that venous invasion, a finding seen in most pancreatic cancers but not in most cancers of other organs, may be a significant, underappreciated contributor to the aggressiveness of this disease. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Estimation of Solid Tumor Doubling Times from Progression-Free Survival Plots Using a Novel Statistical Approach

Tumor doubling time can significantly affect the outcome of anticancer therapy, but it is very challenging to determine. Here, we present a statistical approach that extracts doubling times from progression-free survival (PFS) plots, which inherently contains information regarding the growth of solid tumors. Twelve cancers were investigated and multiple PFS plots were evaluated for each type. The PFS plot showing fastest tumor growth was deemed to best represent the inherent growth kinetics of the solid tumor, and selected for further analysis. The exponential tumor growth rates were extracted from each PFS plot, along with associated variabilities, which ultimately allowed for the estimation of solid tumor doubling times. The mean simulated doubling times for pancreatic cancer, melanoma, hepatocellular carcinoma (HCC), renal cell carcinoma, triple negative breast cancer, non-small cell lung cancer, hormone receptor positive (HR+) breast cancer, human epidermal growth factor receptor-2 positive (HER-2+) breast cancer, gastric cancer, glioblastoma multiforme, colorectal cancer, and prostate cancer were 5.06, 3.78, 3.06, 2.67, 2.38, 2.40, 4.31, 4.12, and 3.84 months, respectively. For all cancers, clinically reported doubling times were within the estimated ranges. For all cancers, except HCC, the growth rates were best characterized by a log-normal distribution. For HCC, the gamma distribution best described the data. The statistical approach presented here provides a qualified method for extracting tumor growth rates and doubling times from PFS plots. It also allows estimation of the distributional characteristics for tumor growth rates and doubling times in a given patient population.

Minimal functional driver gene heterogeneity among untreated metastases

Metastases are responsible for the majority of cancer-related deaths. Although genomic heterogeneity within primary tumors is associated with relapse, heterogeneity among treatment-naïve metastases has not been comprehensively assessed. We analyzed sequencing data for 76 untreated metastases from 20 patients and inferred cancer phylogenies for breast, colorectal, endometrial, gastric, lung, melanoma, pancreatic, and prostate cancers. We found that within individual patients, a large majority of driver gene mutations are common to all metastases. Further analysis revealed that the driver gene mutations that were not shared by all metastases are unlikely to have functional consequences. A mathematical model of tumor evolution and metastasis formation provides an explanation for the observed driver gene homogeneity. Thus, single biopsies capture most of the functionally important mutations in metastases and therefore provide essential information for therapeutic decision-making.

Tumor Volume Doubling Time as a Dynamic Prognostic Marker for Patients with Hepatocellular Carcinoma

BACKGROUND AND AIMS

To evaluate the clinical value of tumor growth rate in hepatocellular carcinoma (HCC) patients, we investigated the growth rate of HCC by calculating the tumor volume doubling time (TVDT) and its impact on survival and recurrence.

METHODS

A retrospective cohort study of 269 HCC patients who underwent two or more pretreatment imaging studies of computed tomography or magnetic resonance imaging was performed. Tumor growth rate and TVDT were calculated by comparing tumor volumes between imaging studies. Clinical parameters independently related to a TVDT of <2 months were evaluated. After dividing patients into slow-growing (159 patients with TVDT >2 months) and rapid-growing (110 patients with TVDT <2 months) groups, we compared the groups in terms of their survival and recurrence outcomes. The response to transarterial chemoembolization (TACE) was evaluated according to TVDT.

RESULTS

The median tumor growth rate and TVDT were 37.5%/month and 2.37 months, respectively. By logistic regression analyses, a high Child-Pugh score, small initial tumor diameter, gross vascular invasion, and tumor multiplicity were found to be independently associated with a TVDT of <2 months (P < 0.05). Patients in the rapid-growing group had lower survival rates and higher recurrence rates (P < 0.05). The response to TACE was worse in the rapid-growing group (P < 0.05).

CONCLUSIONS

A fast HCC growth rate is associated with poor liver function and aggressive tumor biology. HCC patients with shorter TVDTs exhibit poorer survival and recurrence outcomes as well as a poor response to TACE.

Relationship between tumour size and outcome in pancreatic ductal adenocarcinoma

BACKGROUND

The size of pancreatic ductal adenocarcinoma (PDAC) at diagnosis is an indicator of outcome. Previous studies have focused mostly on patients with resectable disease. The aim of this study was to investigate the relationship between tumour size and risk of metastasis and death in a large PDAC cohort, including all stages.

METHODS

Patients diagnosed with PDAC between 1988 and 2013 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Tumour size was defined as the maximum dimension of the tumour as provided by the registry. Metastatic spread was assessed, and survival was calculated according to size of the primary tumour using the Kaplan-Meier method. Cox proportional regression modelling was used to adjust for known confounders.

RESULTS

Some 58 728 patients were included. There were 187 patients (0·3 per cent) with a tumour size of 0·5 cm or less, in whom the rate of distant metastasis was 30·6 per cent. The probability of tumour dissemination was associated with tumour size at the time of diagnosis. The association between survival and tumour size was linear for patients with localized tumours, but stochastic in patients with regional and distant stages. In patients with resected tumours, increasing tumour size was associated with worse tumour-specific survival, whereas size was not associated with survival in patients with unresected tumours. In the adjusted Cox regression analysis, the death rate increased by 4·1 per cent for each additional 1-cm increase in tumour size.

CONCLUSION

Pancreatic cancer has a high metastatic capacity even in small tumours. The prognostic impact of tumour size is restricted to patients with localized disease.

Reconstructing metastatic seeding patterns of human cancers

Reconstructing the evolutionary history of metastases is critical for understanding their basic biological principles and has profound clinical implications. Genome-wide sequencing data has enabled modern phylogenomic methods to accurately dissect subclones and their phylogenies from noisy and impure bulk tumour samples at unprecedented depth. However, existing methods are not designed to infer metastatic seeding patterns. Here we develop a tool, called Treeomics, to reconstruct the phylogeny of metastases and map subclones to their anatomic locations. Treeomics infers comprehensive seeding patterns for pancreatic, ovarian, and prostate cancers. Moreover, Treeomics correctly disambiguates true seeding patterns from sequencing artifacts; 7% of variants were misclassified by conventional statistical methods. These artifacts can skew phylogenies by creating illusory tumour heterogeneity among distinct samples. In silico benchmarking on simulated tumour phylogenies across a wide range of sample purities (15–95%) and sequencing depths (25-800 × ) demonstrates the accuracy of Treeomics compared with existing methods.

Tumours frequently metastasize to multiple anatomical sites and understanding how these different metastases evolve may be important for therapy. Here, the authors develop a method—Treeomics—that can construct phylogenies from multiple metastases from next-generation sequencing data.

CA19-9-related tumor kinetics after first-line chemotherapy of patients with advanced pancreatic cancer: a monoinstitutional experience

The absolute value of carbohydrate antigen 19-9 (CA19-9) pretreatment and its reduction after chemotherapy are established prognostic variables for patients with advanced pancreatic cancer. The present study is a retrospective monoinstitutional evaluation of the prognostic role of the CA19-9 reduction and some CA19-9-related tumor kinetics parameters, such as tumor growth rate constant (G), kinetic tumor response and log ratio. Forty-one cases met the selection criteria. After 8 weeks only G reported an inverse relationship with OS (r = -0.494) that was confirmed by regression analysis (R (2) = 0.192). G after 8 weeks of chemotherapy appears as a possible surrogate end point of overall survival.

Analysis of cancer genomes reveals basic features of human aging and its role in cancer development

Somatic mutations have long been implicated in aging and disease, but their impact on fitness and function is difficult to assess. Here by analysing human cancer genomes we identify mutational patterns associated with aging. Our analyses suggest that age-associated mutation load and burden double approximately every 8 years, similar to the all-cause mortality doubling time. This analysis further reveals variance in the rate of aging among different human tissues, for example, slightly accelerated aging of the reproductive system. Age-adjusted mutation load and burden correlate with the corresponding cancer incidence and precede it on average by 15 years, pointing to pre-clinical cancer development times. Behaviour of mutation load also exhibits gender differences and late-life reversals, explaining some gender-specific and late-life patterns in cancer incidence rates. Overall, this study characterizes some features of human aging and offers a mechanism for age being a risk factor for the onset of cancer.

Somatic mutations are associated with disease, including cancer. Here, the authors analyse cancer genomic data and show that somatic mutations increase with age and that cancer incidence lags 15 years behind this increase, later in life, mutation and cancer incidence are reduced.

Estimation of the Survival Benefit Obtainable From Screening for the Early Detection of Pancreatic Cancer

OBJECTIVE

The chance to improve survival from pancreatic adenocarcinoma relies on early diagnosis through screening, but any screening program is subject to lead-time bias and no data are available in this regard. Aim of the present study was to evaluate the benefit obtainable from a screening program for early detection of pancreatic adenocarcinoma, considering screen-related biases.

METHODS

Monte Carlo simulation was performed using data from 1000 pancreatic cancer patients admitted in a tertiary referral hospital and from pertinent literature. Lead-time bias was assessed and subtracted from expected survival.

RESULTS

Mean expected life expectancy was 13.0 months. Assuming a 20%, 30%, or 50% stage III/IV reduction with screening, pancreatic resections would increase from 217 to 290 in front of a 20% stage III/IV reduction to 324 in front of a 30% reduction and to 385 in front of a 50% reduction. After lead-time adjustment, life expectancies were 14.0, 14.6, and 15.9 months, respectively. The number-needed-to-screen calculation suggests that screening can be harmful in a proportion of patients inversely dependent on the length of follow-up and a significant improvement of survival after diagnosis.

CONCLUSIONS

Pancreatic adenocarcinoma screening program would probably be successful in the presence of a considerable improvement of postdiagnostic survival; otherwise, it only increases surgical procedure amount.

Investigation of Factors Determining the Enhanced Permeability and Retention Effect in Subcutaneous Xenografts

Liposomal chemotherapy offers several advantages over conventional therapies, including high intratumoral drug delivery, reduced side effects, prolonged circulation time, and the possibility to dose higher. The efficient delivery of liposomal chemotherapeutics relies, however, on the enhanced permeability and retention (EPR) effect, which refers to the ability of macromolecules to extravasate leaky tumor vessels and accumulate in the tumor tissue. Using a panel of human xenograft tumors, we evaluated the influence of the EPR effect on liposomal distribution in vivo by injection of pegylated liposomes radiolabeled with (111)In. Liposomal accumulation in tumors and organs was followed over time by SPECT/CT imaging. We observed that fast-growing xenografts, which may be less representative of tumor development in patients, showed higher liposomal accumulation than slow-growing xenografts. Additionally, several other parameters known to influence the EPR effect were evaluated, such as blood and lymphatic vessel density, intratumoral hypoxia, and the presence of infiltrating macrophages. The investigation of various parameters showed a few correlations. Although hypoxia, proliferation, and macrophage presence were associated with tumor growth, no hard conclusions or predictions could be made regarding the EPR effect or liposomal uptake. However, liposomal uptake was significantly correlated with tumor growth, with fast-growing tumors showing a higher uptake, although no biological determinants could be elucidated to explain this correlation.

Missed pancreatic ductal adenocarcinoma: Assessment of early imaging findings on prediagnostic magnetic resonance imaging

OBJECTIVE

To investigate the early imaging findings and growth rate of pancreatic ductal adenocarcinoma (PDAC), and to assess whether MR imaging detects early PDAC better than CT.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the requirement for informed consent. Twenty-two patients were included, and two radiologists, by consensus, assessed the presence of focal lesions, interruption of the main pancreatic duct (MPD), MPD dilatation, and pancreatitis, volume doubling time (VDT) of PDAC on prediagnostic MR imaging. Two other observers independently reviewed three image sets (CT images, unenhanced MR images, and unenhanced and contrast-enhanced MR images) for the detection of early PDAC. Paired Wilcoxon signed rank test and receiver operating characteristic (ROC) curve analysis were used for statistical analyses.

RESULTS

In 20 (90.9%) patients, prediagnostic MR exams showed abnormality, and all of them showed focal lesions on the first abnormal prediagnostic MR exams. Thirteen lesions (65%) showed no MPD interruption and one lesion (5%) was accompanied by pancreatitis. The mean VDT of PDAC was 151.7 days (range, 18.3-417.8 days). Diagnostic performance of unenhanced MR images (Az, 0.971-0.989) and combined unenhanced and contrast-enhanced MR images (Az, 0.956-0.963) was significantly better than that of CT images (Az, 0.565-0.583; p<0.01) for both observers,

CONCLUSION

The most common early imaging finding of PDAC on prediagnostic MR exams was a focal lesion with no MPD interruption with a mean volume doubling time of five months. MR imaging was superior to CT for the detection of early PDAC.

Does a family history of pancreatic ductal adenocarcinoma and cyst size influence the follow-up strategy for intraductal papillary mucinous neoplasms of the pancreas?

OBJECTIVE

This study aimed to evaluate the relationship between pancreatic ductal adenocarcinoma (PDAC) family history and PDAC development in patients followed up for intraductal papillary mucinous neoplasms (IPMNs) and to assess the cyst size relevance in determining follow-up strategies.

METHODS

We analyzed 300 patients with branch duct and mixed-type IPMN who were followed up at our facility.

RESULTS

Among the patients aged 70 years or older, the frequency of PDAC did not differ significantly between those with 1 first-degree relative with PDAC and those without a family history. Although patients with IPMNs of greater than or equal to 30 mm were followed up for a significantly shorter duration than those patients with IPMNs of less than 30 mm, the frequency of IPMN progression and malignant IPMN was significantly greater in the former. The frequency of IPMN progression and pancreatic cancer did not differ significantly according to IPMN size (<10, 10-20, and 20-30 mm) in cases without mural nodules.

CONCLUSIONS

Patients with 1 first-degree relative with PDAC can be followed up using the same criteria for patients without a family history. Special attention should be paid to IPMN progression and malignant transformation in patients with IPMNs of greater than or equal to 30 mm, but cyst size need not be considered when determining follow-up strategies for patients with IPMNs of less than 30 mm without mural nodules.

Analysis of inter-patient variations in tumour growth rate

Purpose

Inter-patient variations in tumour growth rate are usually interpreted as biological heterogeneity among patients due to, e.g., genetic variability. However, these variations might be a result of non-exponential, e.g. the Gompertzian, tumour growth kinetics. The aim was to study if the natural tumour growth deceleration, i.e. non-exponential growth, is a dominant factor in such variations.

Materials and methods

The correlation between specific growth rate (SGR) and the logarithm of tumour volume, Ln(V), was calculated for tumours in patients with meningioma, hepatocellular carcinoma, pancreatic carcinoma, primary lung cancer, post-chemotherapy regrowth of non-small cell lung cancer (NSCLC), and in nude mice transplanted with human midgut carcinoid GOT1, a tumour group which is biologically more homogeneous than patient groups.

Results

The correlation between SGR and Ln(V) was statistically significant for meningioma, post-chemotherapy regrowth of NSCLC, and the mouse model, but not for any other patient groups or subgroups, based on differentiation and clinical stage.

Conclusion

This method can be used to evaluate the homogeneity of tumour growth kinetics among patients. Homogeneity of post-chemotherapy regrowth pattern of NSCLC suggests that, in contrast to untreated tumours, the remaining resistant cells or stem cells (if exist) might have similar biological characteristics among these patients.

Pancreatic cancer: Slow progression in the early stages

INTRODUCTION

The rates of pancreatic cancer development in the early stages of growth remain unclear; but it is generally believed that they demonstrate a rapid degree of progression. There is evidence to suggest that pancreatic cancers measuring less than 1cm demonstrate better survival rates, hence it is clear that detecting pancreatic cancers less than 1cm in size is of paramount importance. However, to date, there has been no scientifically adequate research to show the growth rate of small pancreatic cancers less than 1cm in the early stages.

PRESENTATION OF CASE

We present the case of a 65-year-old woman whose small pancreatic cancer possibly demonstrated a slow progressive rate as it grew to an invasive carcinoma measuring 1cm diameter from over the 29 months.

DISCUSSION

It is reasonable to assume that the progression of some pancreatic cancers until 1cm size, can take up to 29 months. During this silent period, it is crucial to detect such a small pancreatic cancer by means of the initial US and subsequent EUS and ERCP. It is clear, therefore, that clinicians have to be aware of the growth rate of small pancreatic cancers and in particular high risk patients should be encouraged to monitor size of the main pancreatic duct by means of US on regular basis.

CONCLUSION

This could give better outcomes for pancreatic cancer patients. Hopefully, by detecting these lethal, pancreatic cancers in their early stages, it will give us an extension of time to perform effective therapies.

Stereotactic body radiation therapy with concurrent full-dose gemcitabine for locally advanced pancreatic cancer: a pilot trial demonstrating safety

Background

Concurrent chemoradiation is a standard option for locally advanced pancreatic cancer (LAPC). Concurrent conventional radiation with full-dose gemcitabine has significant toxicity. Stereotactic body radiation therapy (SBRT) may provide the opportunity to administer radiation in a shorter time frame with similar efficacy and reduced toxicity. This Pilot study assessed the safety of concurrent full-dose gemcitabine with SBRT for LAPC.

Methods

Patients received gemcitabine, 1000 mg/m² for 6 cycles. During week 4 of cycle 1, patients received SBRT (25 Gy delivered in five consecutive daily fractions of 5 Gy prescribed to the 75-83% isodose line). Acute and late toxicities were assessed using NIH CTCAE v3. Tumor response was assessed by RECIST. Patients underwent an esophagogastroduodenoscopy at baseline, 2, and 6 months to assess the duodenal mucosa. Quality of life (QoL) data was collected before and after treatment using the QLQ-C30 and QLQ-PAN26 questionnaires.

Results

Between September 2009 and February 2011, 11 patients enrolled with one withdrawal during radiation therapy. Patients had grade 1 to 2 gastrointestinal toxicity from the start of SBRT to 2 weeks after treatment. There were no grade 3 or greater radiation-related toxicities or delays for cycle 2 of gemcitabine. On endoscopy, there were no grade 2 or higher mucosal toxicities. Two patients had a partial response. The median progression free and overall survival were 6.8 and 12.2 months, respectively. Global QoL did not change between baseline and immediately after radiation treatment.

Conclusions

SBRT with concurrent full dose gemcitabine is safe when administered to patients with LAPC. There is no delay in administration of radiation or chemotherapy, and radiation is completed with minimal toxicity.

Anticancer nanomedicine and tumor vascular permeability; Where is the missing link?

Anticancer nanomedicine was coined to describe anticancer delivery systems such as polymer conjugates, liposomes, micelles, and metal nanoparticles. These anticancer delivery platforms have been developed with the enhanced permeability and retention (EPR) effect as a central mechanism for tumor targeting. EPR based nanomedicine has demonstrated, beyond doubt, to selectively target tumor tissues in animal models. However, over the last two decades, only nine anticancer agents utilizing this targeting strategy have been approved for clinical use. In this review, we systematically analyze various aspects that explain the limited clinical progress yet achieved. The influence of nanomedicine physicochemical characteristics, animal tumor models, and variations in tumor biology, on EPR based tumor targeting is closely examined. Furthermore, we reviewed results from over one hundred publications to construct patterns of factors that can influence the transition of EPR based anticancer nanomedicine to the clinic.

The aggressiveness of murine lymphomas selected in vivo by growth rate correlates with galectin-1 expression and response to cyclophosphamide

Although lymphomas account for almost half of blood-derived cancers that are diagnosed each year, the causes of new cases are poorly understood, as reflected by the relatively few risk factors established. Galectin-1, an immunoregulatory ß-galactoside-binding protein, has been widely associated with tumor-immune escape. The aim of the present work was to study the relationship between tumor growth rate, aggressiveness, and response to cyclophosphamide (Cy) therapy with regard to Gal-1 expression in murine T-cell lymphoma models. By means of a disruptive selection process for tumor growth rate, we generated two lymphoma variants from a parental T-cell lymphoma, which have unique characteristics in terms of tumor growth rate, spontaneous regression, metastatic capacity, Gal-1 expression and sensitivity to Cy therapy. Here, we show that Gal-1 expression strongly correlates with tumor growth rate, metastatic capacity and response to single-dose Cy therapy in T-cell lymphoma models; this association might have important consequences for evaluating prognosis and treatments of this type of tumors.

Small (≤ 20 mm) pancreatic adenocarcinomas: analysis of enhancement patterns and secondary signs with multiphasic multidetector CT

PURPOSE

To evaluate the enhancement patterns, prevalence of secondary signs, and histopathologic features of 20-mm-diameter or smaller pancreatic cancers seen on multiphasic multidetector computed tomographic (CT) images.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board; the requirement for informed consent was waived. From January 2002 through September 2009, the authors reviewed the clinical and imaging data of 130 consecutive patients (76 men, 54 women; mean age, 64.1 years; age range, 28-82 years) who had surgically proven 30-mm-diameter or smaller pancreatic cancers and underwent preoperative multidetector CT and 33 consecutive patients (17 men, 16 women; mean age, 65.1 years; age range, 48-84 years) who had histopathologically proven pancreatic cancer and underwent incidental multidetector CT before the diagnosis was rendered. Only pancreatic phase CT was performed in two patients, and only hepatic venous phase CT was performed in nine patients. Two radiologists in consensus classified the tumor attenuation as hyper-, iso-, or hypoattenuation during the pancreatic and hepatic venous phases. Accompanying secondary signs, temporal changes in tumor attenuation, and histopathologic findings also were analyzed. The Fisher exact test, χ(2) test, generalized estimating equation, and Student t test were used to compare the variables.

RESULTS

Seventy tumors were 20 mm or smaller, and 93 were 21-30 mm. Isoattenuating pancreatic cancers were more commonly observed among the 20-mm or smaller tumors (16 of 59, 27%) than among the 21-30-mm tumors (12 of 93, 13%) (P = .033). They were also more common among well-differentiated tumors (seven of 12, 58%) than among moderately differentiated (20 of 124, 16%) and poorly differentiated (one of 10, 10%) tumors (P = .001). The prevalence of secondary signs differed significantly according to tumor size (53 [76%] of 70 ≤20-mm tumors vs 92 [99%] of 93 21-30-mm tumors) (P < .001). The prevalence of secondary signs was high among isoattenuating pancreatic cancers (14 [88%] of 16 ≤20-mm tumors vs all 12 [100%] 21-30-mm tumors). Most of the isoattenuating tumors seen at prediagnostic CT were hypoattenuating after 6 months (100% [four of four] during pancreatic phase, 71% [five of seven] during hepatic venous phase).

CONCLUSION

The prevalence of isoattenuating pancreatic cancers differed significantly according to tumor size and cellular differentiation. Most small isoattenuating pancreatic cancers showed secondary signs.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101133/-/DC1.

Growth process of small pancreatic carcinoma: A case report with imaging observation for 22 months

This report describes serial observations of the growth process of a small invasive ductal carcinoma (IDC) of the pancreas from imaging studies. Histopathological studies showed IDC with macroscopic retention cysts proximal to an intraductal papillary-mucinous adenoma with mild atypia of the branch duct type in the pancreatic body, with no relation between the two lesions. IDC was demonstrated as an extremely low-echoic mass resembling a cyst with an unclear margin on the initial endoscopic ultrasonography. We misinterpreted the low-echoic mass as a benign intraductal mucinous-papillary neoplasm (IPMN) based on findings of other imaging studies, and the patient was followed-up. The mass increased from 7 mm to 13 mm in diameter over 22 mo, and remained smaller than 10 mm in diameter for about 420 d. The tumor volume doubling time was 252 d. The Ki67 labeling index was 15.9%, similar to that described in previous reports. Hence, IDC may grow slowly while remaining small.

Specific growth rate versus doubling time for quantitative characterization of tumor growth rate

Doubling time (DT) is widely used for quantification of tumor growth rate. DT is usually determined from two volume estimations with measurement time intervals comparable with or shorter than DT. Clinical data show that the frequency distribution of DT in patients is positively skewed, with some very long DT values compared with the average DT. Growth rate can also be quantified using specific growth rate (SGR; %/d), equal to ln2/DT. The aim of this work was to compare DT and SGR as growth rate variables. Growth rate calculations were computer simulated for a tumor with DT of 100 days, measurement time interval of 1 to 200 days, and volume estimation uncertainty of 5% to 20%. Growth rate variables were determined and compared for previously published clinical data. The study showed that DT is not a suitable variable for tumor growth rate because (a) for short measurement time intervals, or high volume uncertainties, mean DT can either overestimate or underestimate the average growth rate; (b) DT is not defined if the consecutively estimated volumes are equal; and (c) the asymmetrical frequency distribution of DT makes it unsuitable for common statistical testing. In contrast, mean SGR and its equivalent DT give the correct values for average growth rate, SGR is defined for all tumor volume changes, and it has a symmetrical frequency distribution. SGR is also more accurate to use when discussing, for example, growth fraction, cell loss rate, and growth rate heterogeneities within the tumor. SGR should thus be used, instead of DT, to quantify tumor growth rate.

Short time to recurrence after hepatic resection correlates with poor prognosis in colorectal hepatic metastasis

BACKGROUND

Early recurrence is a major problem after hepatic resection of colorectal hepatic metastasis (CHM). Our aim was to investigate the relationship between time to recurrence after CHM resection and overall survival.

METHODS

A retrospective analysis was performed for 101 consecutive patients who underwent hepatic resection for CHM and have been followed more than 5 years.

RESULTS

Among 101 patients, 82 (81%) had a recurrence. Overall survival of patients with recurrence within 6 months after CHM resection was significantly worse than that of patients with recurrence after more than 6 months (P < 0.01). Overall survival was poorer when time to recurrence was shorter. One of the reasons for poor prognosis of patients with recurrence within 6 months was that only a few patients could undergo a second resection for recurrence after CHM resection. Histological type, including poorly differentiated signet ring cell or mucinous adenocarcinoma in the primary tumor, bilobar metastases, microscopic positive surgical margin and carcinoembryonic antigen (CEA) above 15 ng/ml had predictive value for decreased recurrence-free survival after CHM resection.

CONCLUSION

Short time to recurrence after CHM resection correlates with a poor prognosis. Histological type of poorly differentiated signet ring cell or mucinous adenocarcinoma in the primary tumor might be a predictor for early recurrence after CHM resection.

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