Evaluation of the Relationship Between the Incidence of Breast Cancer and Some Anthropometric Variables in Women in Zaria, Nigeria

Evaluation of the Relationship Between the Incidence of Breast Cancer and Some Anthropometric Variables in Women in Zaria, Nigeria.

Chapter One

OBJECTIVES

The objectives of the study are to investigate:

The relationship between body mass index and breast cancer incidence in Nigerian
The relationship between waist – hip ratio and breast cancer incidence in Nigerian women
The relationship between parity and breast cancer incidence in Nigerian women
The relationship between order of birth and breast cancer incidence in Nigerian women
The relationship between age and breast cancer incidence in Nigerianwomen
Possible association of age at menarche and breast cancer incidence in Nigerian women.
Relationship between ethnicity and breast cancer incidence in Nigerian women

CHAPTER TWO

LITERATURE REVIEW

THE BREAST

The breast (mammary gland) is the most important structure in the pectoral region. It is rudimentary in men and becomes fully developed in the females after puberty. It is a modified sweat gland which forms an important accessory organ of the female reproductive system providing nutrition to the new born in the form of milk (Moore and Dalley, 1999).

Anatomy

Situation: It lies in the superficial fascia of the pectoral region. The axillary tail of Spence pierces the deep fascia and lies in the axilla. This may enlarge during lactation in some women and may be mistaken for lump or enlarged lymph nodes (Gray‟s Anatomy, 2004).

Extent: Vertically, it extends from the second or third to the sixth rib. Horizontally, it extends from the lateral border of the sternum to the mid-axillary line (Gray‟s Anatomy, 2004).

Deep relations: The breast lies on the pectoral fascia covering the pectoralis major. Still deeper are the parts of three muscles, namely the pectoralis major, the serratus anterior, and the external oblique muscle of the abdomen. The breast is separated from the pectoral fascia by the loose areolar tissue sometimes called the retromammary space or bursa. Because of the presence of this loose areolar tissue the normal breast can be moved over the pectoralis major (Gray‟s Anatomy, 2004).

CHAPTER THREEE

MATERIALS AND METHODS

STUDY LOCATION

Zaria is a heterogeneous city whose 406990 population (NPC, 2006) comes from different parts of the world. It is second in size only to the State capital, Kaduna. Zaria is located on the high plain of Northern Nigeria 652.6 meters above the sea level, and 950 km away from the coast (Latitude .11^o 07 51N; Longitude 7^o 43 43 E). The town is characterized by gentle rolling plains dotted with groups of rocky residual hills developed on granite bedrock and possesses a tropical continental climate with a pronounced dry season, lasting up to seven months (October- May). Zaria experiences a brief period of hot but dry weather in March and April, followed by a progressive incursion of tropical maritime air mass from the Atlantic Ocean which displaces the (harmattan) winds. During this short period, the mean daily maximum temperatures are fairly stable, and it range from 38º to 42.2º (ABU Portal). Data was collected from the cancer patients undergoing treatment in the Department of Radiotherapy and Oncology, Ahmadu Bello University Teaching Hospital Shika, Zaria. Control group was randomly selected from student and staff of Ahmadu Bello University Zaria.

CHAPTER FOUR

RESULTS

DESCRIPTIVE STATISTICS

Seven hundred and eighteen (718) females of different ethnicity and age range of 17- 75 years participated in this study. The study involved extraction of demographic information and anthropometric parameters. The following anthropometric parameters were taken: weight, height, body mass index, waist circumference, hip circumference, and waist- hip ratio. The demographic information taken were: age, menarcheal age, menopausal age, parity, order of birth, educational level, family history of breast cancer and ethnicity. Histologically confirmed breast cancer cases (n=352) (mean age 45.699 ± 12.363) and control female subjects (n=366) (mean age 26.836 ± 9.536) The result showed that majority of the study participants were overweight (mean BMI 26.847 ± 21.392), and had high waist- hip ratio (mean WHR 0.879 ± 0.135) (Table 4.1). It was observed that the mean value for age, weight, BMI and WHR were higher in the breast cancer group compared to the control group (Table 4.2). Regarding age at menarche, it was found that a number of respondents had a normal age at menarche (Table 4.3) , All the anthropometric variables studied in Table 4.3 were statistically significant (P< 0.001) except for the age at menarche (P= 0.413 ) and height ( P = 0.724)

CHAPTER FIVE

DISCUSSIONS

Overweight and obesity are common health conditions and their prevalence is increasing globally. This case control study revealed that the incidence of breast cancer increased with higher BMI throughout the study population. This is in agreement with the work of Ben Ahmed et al (2011) and Cold et al (2002). Epidemiological evidence found a substantial positive association between BMI and breast cancer risk (Lahmann et al., 2004). One of the most plausible and classical biological explanation is a female hormone-related mechanism because adipose tissue may be a major source of oestrogens (Siiteri, 1987), which are critical mitogens for mammary epithelial cells (Pike et al., 1993; Anderson and Clarke, 2004). Previous studies have provided several potential hormone-related explanations for an increased risk of breast cancer with excess body weight, as follows: increased levels of oestrogen production due to aromatization of androgens in peripheral fat tissue (Siiteri, 1987; Key et al., 2003), and decreased production of sex hormone binding globulin due to obesity (Enriori et al., 1986). These hormone-related mechanisms could increase the supply of free bioavailable oestrogen to breast tissues. In fact, the observed increased risk of breast cancer with increasing BMI was apparently attenuated after adjustment for bioavailable serum oestrogen concentration (Key et al., 2003). Also WHR showed significant association between the breast cancer group and the control group and was seen to be statistically higher in the breast cancer group than in the control group and this is in line with the report of Whincup et al (2001).

CHAPTER SIX

SUMMARY AND CONCLUSION

CONCLUSIONS

In conclusion, neither family history of breast nor parity but BMI and WHR affected breast cancer incidence independently from the anthropometric variables, as found in many other populations similar to a report by Friedenreinch, (2001). This study confirm that early menarche increases breast cancer incidence, to ensure as much comparability as possible between women with breast cancer and control analysis were stratified by these factors; order of birth, ethnic origin and family history of breast cancer. Family history of breast cancer did not have any effect on breast cancer incidence but rather women with no family history of breast cancer had higher incidence of breast cancer. First born women had higher incidence of breast cancer than women born of other ranks in the study population. From this study Hausa women had more incidence of breast cancer compared to Yoruba and Igbo. ( the study location is dominated mainly by the Hausa) Women with higher educational level were seen to have higher incidence of breast cancer when compared to women with lower educational level throughout the study population.

RECOMMENDATIONS

Most of the women used for this study are educated thus it is recommended that research should be carried out investigating the association of breast cancer with lactation and breast size.
More attention to be paid to nutrition and life style habits for improving healthy standards of women in the society by health care
Teaching women and the populace about the hazardous effect of bad lifestyle habits including diet, alcohol intake, and lack of physical exercise is essential for controlling high risk factors of breast cancer which will contribute significantly to a reduction in the incidence of breast cancer in the society

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