Clinical and Epidemiological Characteristics and Surgical Treatment Tactics for Colorectal Cancer in the Republic of Sakha (Yakutia)

The dissertation is devoted to a clinical and epidemiological analysis of colorectal cancer and to the refinement of surgical treatment tactics in the Republic of Sakha (Yakutia). Using regional data for 1991-2007, the study examines the temporal patterns of incidence and mortality from colorectal cancer in different population groups, taking into account sex, age, ethnicity (indigenous and non-indigenous population) and territory of residence (urban and rural population, individual uluses). A component analysis of the growth in incidence was performed, a forecast of the indicators for 2010 was drawn up, and the socio-economic damage caused by mortality from this disease was assessed. The detection rate of background and precancerous diseases of the colon and rectum based on health-care-seeking behaviour was investigated.

A separate line of the work concerns the surgical treatment of complicated forms of colorectal cancer. A comparative analysis of the short-term results of treatment in two observation periods (1989-2004 and 2005-2007) was carried out, and an improved diagnostic and treatment algorithm, based on a "scale of signs" and an integral assessment of the severity of the patients' condition, was developed and introduced. The results obtained have been implemented in the clinical practice of surgical departments of the Republic of Sakha (Yakutia) and in the teaching process of Yakutsk State University.

Relevance of the study. Every year about 800 thousand new cases of colon and rectal cancer and 440 thousand deaths from this disease are registered worldwide (Martynyuk V.V., 2000).

In 2006, more than 53.7 thousand new cases of malignant tumours of colorectal localisation were detected in Russia, which exceeded the number of cases registered in 1995 (40.9 thousand) by more than 23.8%. The age-standardised incidence rate (ASIR) for colon cancer reached 14.8 in men and 12.0 per 100,000 population in women, and for rectal cancer it reached 13.9 and 8.5 per 100,000 population, respectively. The male-to-female ratio amounted to 1.2:1.0. The greatest number of cases falls within the age group over 60 years, while the maximum level of oncological incidence is recorded in the age group over 75 years (Chissov V.I. et al., 1997-2007; Davydov M.I., Aksel E.M., 2002; 2005-2008).

In the Republic of Sakha (Yakutia), within the overall structure of oncological incidence, colorectal cancer accounts for 9.1% in men and 11.3% in women, while among other localisations of malignant tumours of the digestive organs, colorectal cancer (21.6%) is second in frequency only to gastric cancer (30.5%). Over the recent decades (1995-2005), the age-standardised incidence rates of colorectal cancer increased in men from 15.3 to 26.8 and in women from 14.1 to 20.5 per 100,000 population. The one-year case fatality rate from the moment of diagnosis amounts to 55.0% (Ivanov P.M. et al., 2000, 2003, 2008).

According to B.S. Zaporozhchenko et al. (1999), the majority of patients admitted to hospitals present with stage III-IV disease, and many of them exhibit various complications (obstructive intestinal obstruction, tumour perforation, bleeding, and perifocal inflammation) that require emergency surgical intervention. The most frequent and severe complication is intestinal obstruction (from 15 to 72.5%) (Grinev M.V. et al., 2002; Pastukhov A.A. et al., 2005), with mortality reaching up to 52% (Aliev S.A., 1997, 1999; Pakhomova G.V. et al., 2003). A tendency towards an increase in the number of patients with a colostomy has been noted, which leads to a decrease in working capacity and a rise in disability among the working-age population, which in turn results in greater socio-economic losses to the state.

In this connection, a detailed study of the spatial and temporal characteristics of colorectal cancer, including an assessment of the role of risk factors and an analysis of the causes of unsatisfactory preventive, diagnostic and therapeutic measures, becomes highly relevant. These issues, as applied to the regional conditions of Yakutia, constitute a theoretically new and serious problem. Undoubtedly, such approaches will make it possible to formulate concrete, evidence-based programmes for improving the oncological situation in the region.

Aim of the study: to improve the results of diagnosis and surgical treatment of patients with colorectal cancer.

Objectives of the study:

1. To investigate the temporal patterns of incidence and mortality from CRC in different population groups of Yakutia over 1991-2005 and to forecast the indicators for 2010;

2. To study the detection rate of background and precancerous diseases of the colon and rectum based on health-care-seeking behaviour;

3. To develop an algorithm for the diagnosis of colorectal cancer under the conditions of Yakutia;

4. To carry out a comparative analysis of the short-term results of treatment of patients with complicated colorectal cancer depending on the surgical tactics employed in the first (1989-2004) and second (2005-2007) periods of observation;

5. To determine the level of socio-economic damage caused by mortality from CRC in the Republic of Sakha (Yakutia).

Scientific novelty. For the first time, on the basis of a detailed study of the oncological situation, the territorial, ethnic and age-related features of colorectal cancer incidence and mortality in the population of the Republic of Sakha (Yakutia) have been analysed, a forecast has been made and the socio-economic damage has been calculated. Mapping of the territorial features of colorectal cancer distribution in Yakutia has been performed.

The organisational approaches to improving the effectiveness of specialised care for CRC under the conditions of the North have been substantiated and developed. An improved diagnostic and treatment algorithm, based on the use of a "scale of signs" and an integral assessment of the severity of the patients' condition in the treatment of complicated forms of colorectal cancer, has been developed and introduced.

Practical significance. On the basis of the results obtained, evidence-based practical recommendations for the prevention, diagnosis and treatment of colorectal cancer, tailored to the conditions of the North, have been developed. To improve the results of surgical treatment of patients with colorectal cancer, an improved diagnostic and treatment algorithm has been elaborated.

The results obtained are used in the everyday clinical practice of the surgical departments of RB No. 2-TsEMP, the Yakutsk Republican Oncological Dispensary, and the central ulus hospitals. The main propositions of the dissertation are used in the teaching process during classes with third- to sixth-year students at the surgical departments of the Medical Institute of Yakutsk State University and the Institute of Postgraduate Medical Training.

Main propositions submitted for defence.

1. Under the conditions of Yakutia, colorectal cancer occupies one of the leading places in the structure of oncological incidence and shows a clearly pronounced dependence on sex, age, ethnicity and territory, with a tendency towards further growth.

2. In the dynamics of CRC incidence, changes in the size and age structure of the population play an important role for the non-indigenous population, while the influence of risk factors plays an important role for the indigenous population.

3. The introduction of an algorithm of surgical tactics for the treatment of patients with complicated colorectal cancer has made it possible to significantly improve the short-term results of surgical treatment of patients with this form of malignant tumours.

Approval of the dissertation. The main propositions of the dissertation were reported and discussed at: the XI-XIV Republican Conferences of Oncologists of Yakutia (Yakutsk, 2006, 2007, 2008); the 11th International Medical Symposium in Japan ("The Eleventh International Symposium of The Japan-Russia Medical Exchange", Niigata, 2004); the Russian Conference dedicated to the 25th anniversary of the Research Institute of Oncology of the Tomsk Scientific Centre of the Siberian Branch of the Russian Academy of Medical Sciences "Current State and Prospects of Development of Experimental and Clinical Oncology" (Tomsk, 24-25 July 2004); the III Congress of Oncologists and Radiologists of the CIS (Minsk, 2004); the Inter-Zonal Conference of Oncologists "Precancerous Conditions of the Digestive Organs under the Conditions of the Far North" (Novosibirsk, 2006); the Republican Conference "Life Safety in the Republic of Sakha (Yakutia)" (Yakutsk, 2006); and the Republican Conference "Actual Problems of Emergency Medical Care" (Yakutsk, 2008).

Scope and structure of the dissertation. The work is set out on 167 pages of typewritten text and consists of an introduction, a literature review, a description of the materials and methods of the study, four chapters of original research, a conclusion, conclusions, practical recommendations, and a reference list comprising 241 sources (162 Russian and 79 foreign authors). The work is illustrated with 12 figures and 45 tables.