Tax constitutional model and social rights
2. Deber constitucional de tributar
the netherlands number % canada number % p-value Age 0.64 <65 years 65 48.5 68 48.2 65-74 years 45 33.6 42 29.8 ≥75 years 24 17.9 31 22.0 Gender 0.35 Male 90 67.2 102 72.3 Female 44 32.8 39 27.7 clinical t-stage cT3 134 100.0 141 100.0 clinical n-stage 0.04 Negative 65 48.5 90 63.8 Positive 66 49.3 49 34.8 Unknown 3 2.2 2 1.4 Year of surgery 0.33 2005 22 16.4 25 17.7 2006 16 12.0 28 19.9 2007 29 21.6 23 16.3 2008 28 20.9 20 14.2 2009 24 17.9 29 20.6 2010 15 11.2 16 11.3 total 134 48.7 141 51.3
table 2: Postoperative T-stage and N-stage
the netherlands number % canada number % p-value Pathological t-stage <0.001 ypT0 15 11.2 45 31.9 1 4 3.0 13 9.2 2 37 27.6 42 29.8 3 72 53.7 39 27.7 4 2 1.5 2 1.4 Unknown 4 3.0 0 0.0 Pathological n-stage 0.11 0 83 61.9 103 73.1 1 36 26.9 24 17.0 2 15 11.2 14 9.9 total 134 48.7 141 51.3
with a higher percentage of pathological complete responses (ypT0) (11.2% in patients treated with 5×5 Gy or CRT, as compared with 31.9% in patients treated with HDREBT) and fewer pathological T3-stage (53.7% patients treated with 5×5 Gy or CRT, 27.7% patients treated with HDREBT). The pN-stage on the other hand, did not differ significantly between both countries (p=0.11), although patients treated with HDREBT seemed to have slightly more pathological positive lymph nodes (73.1%, compared with 61.9% in patients treated with 5×5 Gy or CRT).
Figure 1 shows the five year overall survival for the countries. Comparing the five year overall survival between patients treated with 5×5 Gy or CRT and patients treated with HDREBT unadjusted for baseline imbalances showed a HR of 0.56 (95% CI 0.27-1.16, p=0.12). After adjustment for potential confounders, patients treated with HDREBT had a significant better five year overall survival (HR 0.39, 95% CI 0.16-0.93, p=0.03). When comparing five year cancer-specific mortality between the countries, 6/134 patients treated with 5×5 Gy or CRT died due to the rectal cancer, and 4/141 patients treated with HDREBT (HR 0.59, 95% CI 0.16-2.08, p=0.41). Five-year local recurrence was 5/134 in the patients treated with 5×5 Gy or CRT and 2/141 in the patients treated with HDREBT (HR 0.54, 95% CI 0.13-2.28, p=0.41). When death was taken into account as competing risk, the SHR for five year cancer-specific mortality was 0.60 (95% CI 0.17-2.16, p=0.44), and the SHR for five year local recurrence was 0.56 (95% CI 0.14-2.30, p=0.42). 0. 00 0. 25 0. 50 0. 75 1. 00 141 115 84 57 39 16 Canada 134 101 74 49 26 12
The NetherlandsNumber at risk
0 1 2 3 4 5
Years since surgery
The Netherlands Canada
9
There was no difference in five year overall survival between Dutch patients treated with 5×5 Gy radiotherapy and Dutch patients treated with CRT after adjustment (HR 1.18, 95% CI 0.32- 4.35, p=0.80).
DiscussiOn
In this study, a comparison was made between the current standard preoperative therapy in the Netherlands (5×5 Gy or CRT) and a newer therapy used in Canada, HDREBT. Overall survival was better for patients treated with HDREBT. Cancer-specific mortality and local recurrence were comparable, although this comparison is based on few events, making the study underpowered to detect relevant differences. Overall, the results of this study suggest that HDREBT could be a safe alternative to CRT or 5×5 Gy in the treatment of patients with rectal cancer.
Findings from the present study add important new observations, which to our knowledge, have not been previously investigated. The results show that overall survival was better for patients treated with HDREBT, as compared with patients treated with 5×5 Gy or CRT. Besides, only a few patients had a local recurrence or died due to rectal cancer in both countries. The results of this study should be interpreted with caution, since the data are observational and type of preoperative treatment has not been randomised. The study’s conclusions there- fore rely on the assumption of no unmeasured confounding. We have tried to deal with the potential of confounding by design and by analysis. We used a design in which the level of comparison was between two countries. The comparison at country level emulates the prin-
ciples of an instrumental variable analysis18,19, which deals with (unmeasured) confounding
because the instrument (in this case country) is at least partially unrelated to prognosis. In other words: we made the assumption that the cT3 patients treated in the Netherlands and in Canada where to a certain extent comparable. As a direct country comparison will not circum- vent confounding completely, we also adjusted for important baseline differences between the countries. Moreover, differences in age, gender, cN-stage, and year of surgery were found when comparing the two countries at baseline. These variables were adjusted for in the analysis. Clinical N-stage was significantly different between patients treated with 5×5 Gy or CRT and HDREBT when compared preoperative (p=0.004), but after surgery, no significant dif- ferences in N-stage between both countries were found. Differences in preoperative N-stage could be due to difference in staging by the radiologists as accuracy of positive lymph nodes
identification in rectal cancer lacks.20,21 In addition, the differences preoperatively could be
decreased or adjusted due to the type of preoperative treatment used within the country, since preoperative treatment involves radiation on lymph nodes. Even though, the type of preoperative treatment was based on the cT-stage and in lesser extent on cN-stage.
Unexpectedly, the overall survival between the countries was significantly better for patients treated with HDREBT. We hypothesize that HDREBT is associated with lower non-cancer related deaths in comparison with external beam radiotherapy. This is an important observation as the long term results from the Dutch trial suggested that despite the improved cancer-specific survival provided by radiation therapy, these benefits were nullified by an increase in other
causes of death.22 One of the main causes was secondary cancer.22 Several other studies on
prostate cancer have also shown that secondary malignancies are less common after HDREBT
as compared to external beam radiation.23-26 Furthermore, in the current study no difference
between both countries is present until 4 years since surgical treatment, which suggests that short term outcome does not differ between both treatment strategies, as also shown in a
comparison between patients from Canada and Sweden.27
An ypT0 stage has been achieved more often for patients treated with preoperative HDREBT as compared with the treatment strategy from the Netherlands. Since 5×5 Gy is often followed by immediate surgery and downstaging is not the aim of this short course of radiation, this could explain the differences in downstaging. CRT on the other hand is followed by surgery after at least 6 weeks, similar to HDREBT, which would expect the same percentage of downstaging. However, HDREBT does induce more downstaging as compared with CRT as the mean dose given to the tumour bed was 26 Gy in 4 days, which is a much higher radiobiological dose than
45-50 Gy in 25-28 fractions.28-30
HDREBT was introduced as an attempt to reduce radiation treatment-related toxicity. The initial results showed that all patients treated with preoperative HDREBT had an acute proctitis grade 2, except one percent of patients who had an acute proctitis grade 3 and required a blood
transfusion. None of the patients had to be hospitalized for treatment-related toxicity.10 A
comparison between Sweden and HDREBT showed that the postoperative complications were similar between patients treated with HDREBT, 5×5 Gy and without preoperative treatment, except HDREBT had a higher rate of cardiovascular complications, but there was no increase
in the postoperative deaths.27 This could possibly be explained by the higher Charlson
comorbidity score in the Canadian population (data not shown). Furthermore, a comparison of hormonal profile collected prospectively in 119 male patients with rectal cancer treated with either conventional CRT or HDREBT showed that HDREBT allows better hormonal spar-
ing, less hypogonadism.31 And finally, interim analyses of an on-going study show that both
faecal incontinence and urinary incontinence are lower in patients treated with HDREBT in
comparison with patients treated with external beam radiotherapy.32 All these studies suggest
9
cOnclusiOn
Overall, HDREBT seems to be a realistic alternative in the treatment of patients with rectal cancer, whereas postoperative complications, local recurrence rates and the rates of death due to rectal cancer were low in all countries. These findings could have profound clinical implications and strongly propose a randomized controlled trial in consideration of the pos- sible overall survival benefits suggested by this study, in addition to a lower overall treatment- related toxicity.
reference list
1 Ferlay J, Shin HR, Bray F et al. Estimates of worldwide burden of cancer in 2008: GLOBO-
CAN 2008. Int J Cancer 2010; 127: 2893-917.
2 Improved survival with preoperative radio- therapy in resectable rectal cancer. Swedish
Rectal Cancer Trial. N Engl J Med 1997; 336:
980-7.
3 Heald RJ, Ryall RD. Recurrence and survival after total mesorectal excision for rectal
cancer. Lancet 1986; 1: 1479-82.
4 MacFarlane JK, Ryall RD, Heald RJ. Mesorectal
excision for rectal cancer. Lancet 1993; 341:
457-60.
5 Peeters KC, Marijnen CA, Nagtegaal ID et al. The TME trial after a median follow-up of 6 years: increased local control but no survival benefit in irradiated patients with resectable
rectal carcinoma. Ann Surg 2007; 246: 693-
701.
6 Adjuvant radiotherapy for rectal cancer: a systematic overview of 8,507 patients from
22 randomised trials. Lancet 2001; 358:
1291-304.
7 Camma C, Giunta M, Fiorica F et al. Preopera- tive radiotherapy for resectable rectal cancer:
A meta-analysis. JAMA 2000; 284: 1008-15.
8 Marijnen CA, Kapiteijn E, van de Velde CJ et al. Acute side effects and complications after short-term preoperative radiotherapy combined with total mesorectal excision in primary rectal cancer: report of a multicenter
randomized trial. J Clin Oncol 2002; 20: 817-
25.
9 Peeters KC, van de Velde CJ, Leer JW et al. Late side effects of short-course preoperative radiotherapy combined with total mesorectal excision for rectal cancer: increased bowel dysfunction in irradiated patients--a Dutch
colorectal cancer group study. J Clin Oncol
2005; 23: 6199-206.
10 Vuong T, Devic S, Podgorsak E. High dose rate endorectal brachytherapy as a neoadjuvant treatment for patients with resectable rectal
cancer. Clin Oncol (R Coll Radiol ) 2007; 19:
701-5.
11 Devic S, Vuong T, Moftah B. Advantages of inflatable multichannel endorectal applicator in the neo-adjuvant treatment of patients
with locally advanced rectal cancer with HDR
brachytherapy. J Appl Clin Med Phys 2005; 6:
44-9.
12 Devic S, Vuong T, Moftah B et al. Image-guided high dose rate endorectal brachytherapy. Med Phys 2007; 34: 4451-8.
13 Vuong T, Belliveau PJ, Michel RP et al. Confor- mal preoperative endorectal brachytherapy treatment for locally advanced rectal cancer:
early results of a phase I/II study. Dis Colon
Rectum 2002; 45: 1486-93.
14 Vuong T, Devic S, Moftah B, Evans M, Podgorsak EB. High-dose-rate endorectal brachytherapy in the treatment of locally advanced rectal carcinoma: technical aspects. Brachytherapy 2005; 4: 230-5.
15 Vuong T, Richard C, Niazi T et al. High Dose Rate Endorectal Brachytherapy for Patients
With Curable Rectal Cancer. Semin Colon
Rectal Cancer Surg 2010; 21: 115-9. 16 Dutch guidelines for the treatment of oncol-
ogy. http: //www.oncoline.nl (accessed May 31 2013).
17 Putter H, Fiocco M, Geskus RB. Tutorial in biostatistics: competing risks and multi-state
models. Stat Med 2007; 26: 2389-430.
18 Brookhart MA, Rassen JA, Schneeweiss S. Instrumental variable methods in compara-
tive safety and effectiveness research. Phar-
macoepidemiol Drug Saf 2010; 19: 537-54. 19 Rassen JA, Brookhart MA, Glynn RJ, Mittleman
MA, Schneeweiss S. Instrumental variables I: instrumental variables exploit natural varia- tion in nonexperimental data to estimate
causal relationships. J Clin Epidemiol 2009;
62: 1226-32.
20 Bipat S, Glas AS, Slors FJ et al. Rectal cancer: local staging and assessment of lymph node involvement with endoluminal US, CT, and MR
imaging--a meta-analysis. Radiology 2004;
232: 773-83.
21 Lahaye MJ, Engelen SM, Nelemans PJ et al. Imaging for predicting the risk factors--the circumferential resection margin and nodal disease--of local recurrence in rectal cancer:
a meta-analysis. Semin Ultrasound CT MR
9
22 van Gijn W, Marijnen CA, Nagtegaal ID et al. Preoperative radiotherapy combined with total mesorectal excision for resectable rectal cancer: 12-year follow-up of the multicentre,
randomised controlled TME trial. Lancet
Oncol 2011; 12: 575-82.
23 Bhojani N, Capitanio U, Suardi N et al. The rate of secondary malignancies after radical prostatectomy versus external beam radia- tion therapy for localized prostate cancer: a population-based study on 17,845 patients. Int J Radiat Oncol Biol Phys 2010; 76: 342-8. 24 Brenner DJ, Curtis RE, Hall EJ, Ron E. Second
malignancies in prostate carcinoma patients after radiotherapy compared with surgery. Cancer 2000; 88: 398-406.
25 Liauw SL, Sylvester JE, Morris CG, Blasko JC, Grimm PD. Second malignancies after pros- tate brachytherapy: incidence of bladder and colorectal cancers in patients with 15 years
of potential follow-up. Int J Radiat Oncol Biol
Phys 2006; 66: 669-73.
26 Zelefsky MJ, Housman DM, Pei X et al. Inci- dence of secondary cancer development after high-dose intensity-modulated radio- therapy and image-guided brachytherapy for
the treatment of localized prostate cancer. Int
J Radiat Oncol Biol Phys 2012; 83: 953-9. 27 Hesselager C, Vuong T, Pahlman L et al. Neo-
adjuvant high dose endorectal brachytherapy or short course external beam radiotherapy in
resectable rectal cancer. Colorectal Dis 2013.
28 Kalady MF, de Campos-Lobato LF, Stocchi L et al. Predictive factors of pathologic complete response after neoadjuvant chemoradiation
for rectal cancer. Ann Surg 2009; 250: 582-9.
29 Moore HG, Gittleman AE, Minsky BD et al. Rate of pathologic complete response with increased interval between preoperative combined modality therapy and rectal cancer
resection. Dis Colon Rectum 2004; 47: 279-
86.
30 Tulchinsky H, Shmueli E, Figer A, Klausner JM, Rabau M. An interval >7 weeks between neoadjuvant therapy and surgery improves
pathologic complete response and
disease-free survival in patients with locally
advanced rectal cancer. Ann Surg Oncol 2008;
15: 2661-7.
31 Yau I, Vuong T, Garant A et al. Risk of hypo- gonadism from scatter radiation during pelvic radiation in male patients with rectal cancer. Int J Radiat Oncol Biol Phys 2009; 74: 1481-6. 32 Al-Halabi H, Poggi L, Niazi T et al. Functional
and Quality of Life Assessment in Rectal Cancer Patients Treated with Pre-operative Endorectal Brachytherapy and Sphincter
Preserving Surgery. Int.J.Radiat.Oncol.Biol.