Metastatic Brain Tumors in Two Predominantly Black Hospitals: A Statistical Analysis Kuang-Jaw Fan, MD, and Joseph Kovi, MD Washington, DC
A retrospective statistical analysis was done on metastatic brain tumors collected from two predominantly black hospitals in Washington, DC. A composite African series of metastatic brain tumors was also constructed for comparison. The results indicate that bronchogenic carcinoma is the predominant metastatic brain tumor (45.2 percent) among American blacks in Washington, DC, and chorioepithelioma, the most common (20.0 percent) among African blacks. In comparing these two series, much dissimilarity in the pattern of tumor distribution between these two genetically related ethnic groups suggests an important environmental role in the genesis of metastatic brain tumors. The present study also reveals a relatively high proportional frequency of prostatic carcinoma among metastatic brain tumors in blacks (3.8 percent in Washington, DC, and 2.1 percent in Africa).
The importance of a genetic role in the genesis of primary tumors in the central nervous system has been emphasized by previous authors through a statistical analysis of 17,035 cases of primary central nervous system tumors. I It clearly indicated that American blacks had a much higher frequency of meningioma and pituitary adenoma as compared to American Caucasians. A similar pattern of tumor distribution (proportional frequency) of various primary central nervous system tumors between American and African blacks was also demonstrated in that study. General information on metastatic brain tumors in predominantly white communities has been abundant in the literature.27 However, comparable information on metastatic brain Presented in part at the Eighth International Congress of Neuropathology, Washington, DC, September 27 1978. Requests for reprints should be addressed to Dr. Kuang-Jaw Fan, Department of Pathology, Howard University, College of Medicine, 520 W Street NW, Washington, DC 20059.
tumors in American blacks has not been substantially available. The purpose of this study is to elucidate the pattern of distribution of metastatic brain tumors in American blacks through a statistical analysis of accumulated material from two predominantly black hospitals in Washington, DC. An attempt is made also to compare these results with those of African blacks to determine whether genetic or environmental factors play a more important role in the genesis of metastatic brain tumors.
Materials and Methods Howard University Hospital and DC General Hospital are two predominantly black hospitals in Washington, DC. Traditionally, the great majority of patients in these two hospitals have been black. From 1954 to 1973, the departments of pathology in these two hospitals had diagnosed 306 cases of brain tumor, including necropsy and
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 7, 1979
surgical cases. Among them, 104 cases were metastatic. They were classified into subgroups (proportional frequency) according to primary site. A further analysis, according to age and sex distribution, was also made. The pattern of 'metastatic brain tumors (proportional frequency) in these two institutions was then contrasted to that of a composite African series. It was constructed from scattered published data on metastatic brain tumors from Uganda,8'0 Ivory Coast," Nigeria,'2 Kenya,'3"14 Zambia,'5 and Senegal.'6 All acceptable cases of metastatic brain tumors reported from 1953 to 1971 were
included. To avoid unnecessary confusion, only metastatic tumors found in the brain substance were included in this study. Tumors involving the epidural space or extending directly from adjacent structures were carefully excluded. Due to insufficient information on age and sex from African cases, further analysis of the composite African series was not possible. 671
Results Table 1 indicates that metastatic tumor was the most common tumor in the brain (34.0 percent) in these two predominantly black hospitals. Glioma, meningioma, and pituitary adenoma, in that order, were the three leading primary intracranial tumors, 25.8, 20.3, and 13.1 percent, respectively. When the metastatic brain tumors were
Table 1. Primary and Metastatic Brain Tumors by Histologic Type, Howard University and DC General Hospitals, 1954 to 1973 Tumor Type
Glioma Medulloblastoma Meningioma Pituitary adenoma Metastatic tumor Others Total
Case
%
79 7 62 40 104 14
25.8 2.3 20.3 13.1 34.0 4.6 100
306
classified into subgroups according to primary site (Table 2), it clearly was indicated that those of lung origin outnumbered the total of the other known primary sites. The second most common metastatic tumor was from breast (10.6 percent). Tumors from the kidney and prostate comprised 3.8 percent, each. When this series was compared to a composite African series, the patterns of tumor distribution (proportional frequency) differed greatly. The most common metastatic brain tumor in the African series was primary to the uterus (chorioepithelioma 20.0 percent). Tumors from the lung and breast comprised only 14.7 and 5.3 percent, respectively. In general, metastatic brain tumors in Africans were more diversely distributed from various primary sites as compared to those in Anmericans. In fact, approximately 30 percent of metastatic tumors rose from the skin (melanomna), soft tissue, liver, GI tract, and nasopharynx in the composite African series. Metastatic brain tumors in the authors' series were tabulated according to sex and primary site (Table 3).
Table 2. Metastatic Brain Tumors by Primary Site, Howard University and DC General Series (1954-1973) and Composite African Series (1953-1971)*
ICD** Number
Primary Site
142 146-9, 160 151-154 155.0 157 162 163.0 170-1 172-3 174 181 183-4 185 188 189.0 190 193 194.0 199 200
Salivary gland Nasopharynx Gl tract Liver Pancreas Lung Pleura Soft tissue Skin (melanoma) Breast Uterus (chorioepthelioma) Ovary, etc Prostate Bladder Kidney Eye Thyroid gland Adrenal Unknown Lymphoma, etc Total
Howard DC General % Case 0 1 2 1 2 47 0 1 3 11 0 1 4 0 4 0 0 2 25 0 104
0.0 1.0 1.9 1.0 1.9 45.2 0.0 1.0 2.9 10.6 0.0 1.0 3.8 0.0 3.8 0.0 0.0 1.9 24.0 0.0 100
*As indicated in Materials and Methods number (International Classification of Diseases)23
**Classification 672
African Series % Case 1 4 6 6 0 14 1 5 7 5 19 2 2 1 2 1 3 0 14 2 95
1.1 4.2 6.3 6.3 0.0 14.7 1.1 5.3 7.4 5.3 20.0 2.1 2.1 1.1 2.1 1.1 3.2 0.0 14.7 2.1 100
The major source of metastatic brain tumor among males was lung (52.2 percent). The second most common primary sites were kidney and prostate, which comprised only 5.8 percent of metastatic brain tumors in males. In females, the breast and lung were the two most common primary sites and they each comprised 31.4 percent of metastatic brain tumors. Metastatic brain tumors were tabulated by sex and age (Table 4). The peak age group for metastatic brain tumors in both sexes was 50 to 59 years. However, such tumors were more evenly distributed among various age groups in the female. In fact, the relative frequency of metastatic brain tumors among the age group, 30 to 49, was much higher in the female than the male sample.
Discussion The pattern of distribution (proportional frequency) of various metastatic brain tumors in both series generally reflected the relative frequency of the individual tumor at its primary site. However, it should be mentioned that metastatic brain tumor of prostate origin in these two series was much more common than general belief (3.8 percent in Washington, DC, and 2.1 percent in Africa). It has been stated that prostatic carcinoma rarely or never metastasizes to brain substance.7 A recent report of a literature review indicated that only 0.8 percent of metastatic brain tumors (ten of 1,202 cases) were from the prostate.'7 Although the relatively high frequency of prostatic carcinoma among metastatic brain tumors in our series was in line with the high incidence of prostatic carcinoma in the black population of Washington, DC,18 the frequency of this tumor to metastasize to the brain was still considered to be relatively low as compared to that of bronchogenic carcinoma. Prostatic carcinoma was shown to be slightly more common than bronchogenic carcinoma among males in Washington, DC. 18 In the composite Africian series, chorioepithelioma outnumbered bronchogenic carcinoma as the most common metastatic brain tumor. This result was apparently due to the high inci-
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 7, 1979
dence of chorioepithelioma in Africa and the high tendency of this tumor to metastasize to the brain.'1922 The importance of a genetic role in the genesis of primary brain tumors was suggested previously through a comparison of primary brain tumors between American and African blacks. ' It clearly indicated a similarity of tumor distribution (proportional frequency) of primary brain tumors between the two genetically and closely related ethnic groups. In contrast, a much different pattern of tumor distribution of metastatic brain tumors between the two ethnic groups indicated in this study perhaps emphasizes the importance of non-genetic factors in the development of metastatic brain tumors. Since the brain substance is well protected from the physical environment by a rigid skull, and the rather unique blood-brain barrier keeps the brain substance from being exposed to many noxious chemical agents circulating in the blood, it is conceivable that environmental factors play a less important role in the genesis of primary intracranial tumors than in that of extracranial tumors. These data, in conjunction with those from a previous study,' suggest that the genesis of metastatic brain tumors is influenced more by indirect environmental factors than by genetic factors.
Table 3. Metastatic Brain Tumors by Sex and Primary Site, Howard University and DC General Hospitals, 1954 to 1973 ICD Number 146-9, 160 151-154 155.0 157 162 170-1 172-3 174 183-4 185 189.0 194.0 199
Primary Site
Male
Nasopharynx Gl tract Liver Pancreas Lung Soft tissue Skin (melanoma) Breast Ovary, etc Prostate Kidney Adrenal Unknown Total
Case
%
1 1 1 1 36 0 2 0 0 4 4 2 18 69
1.5 1.5 1.5 1.5 52.2 0.0 2.9 0.0 0.0 5.8 5.8 2.9 26.1 100
Female Case % 0 1 0 1 11 1 1 11 1 0 0 0 7 35
0.0 2.9 0.0 2.9 31.4 2.9 2.9 31.4 2.9 0.0 0.0 0.0 25.7 100
Table 4. Metastatic Brain Tumors by Age and Sex, Howard University and DC General Hospitals, 1954 to 1973
Age 0-9 30-39 40-49 50-59 60-69 70-
Unknown Total
Case
Male
3 4 10 30 14 6 2 69
%Case% 4.3 5.8 14.5 43.5 20.3 8.6 2.9 100
0 5 8 10 6 3 3 35
Female 0.0 14.3 22.9 28.6 17.1
8.6 8.6 100
Acknowledgement The authors thank Dr. Sophie Perry for providing material from DC General Hospital.
Literature Cited 1. Fan KJ, Kovi J, Earle KM: The ethnic distribution of primary central nervous system tumors: Armed Forces Institute of Pathology, 1958 to 1970. J Neuropathol Exp Neurol 36:4149, 1977 2. Earle KM: Metastatic brain tumors. Dis Nerv Syst 16:86-92, 1955 3. Kernohan JW, Sayre GP: Tumors of the central nervous system, In: Atlas of Tumor Pathology, Fasc. 35. Washington, DC, Armed Forces Institute of Pathology, 1952, pp 17-58 4. Meyer PC, Reah TG: Secondary neoplasms of the central nervous system and meninges. Br J Cancer 7:438-448, 1953 5. Rubinstein LJ: Tumors of the central nervous system. In: Atlas of Tumor Pathology, series 2. Fasc. 6, Washington, DC, Armed Forces Institute of Pathology, 1972, pp 313-332 6. Russel DS, Rubinstein LJ: Pathology of Tumours of the Central Nervous System, ed 3. London, Edward Arnold, 1971, pp 261-272 7. Willis RA: Secondary tumors. In Minckler J (ed): Pathology of the Nervous System, vol 2. New York, McGraw-Hill, 1971, pp
2178-2196 8. Bailey IC: The pattern and presentation of intracranial tumors in Uganda. East Afr Med J 48:565-575, 1971 9. Billinghurst JR: Intracranial spaceoccupying lesions in African patients at Mulago Hospital, Kampala. East Afr Med J 43:385-393, 1966 10. Templeton AC: Tumours of the brain: Recent results. Cancer Res 41:200-202, 1973 11. Giordano C: Tumeurs du systeme nerveux en Cote d'lvoire. Afr J Med Sci 4:197-207, 1973 12. Odeku EL, Osuntokun BO, Williams AO: Tumors of the brain and its coverings: An African series. Int Surg 57:798-801, 1972 13. Kasili EG, Cameron HM, Ruberti RF, et al: Histopathology of brain tumors in the African in Kenya. Afr J Med Sci 4:99-106, 1973 14. Ruberti RF, Poppi M: Tumours of the central nervous system in the African. East Afr Med J 48:576-584, 1971 15. Chuke PO. Mathew TM, Naik GG: Tumours of the central nervous system in Zambia. Afr J Med Sci 4:107-110, 1973 16. Collomb H, Quenum C, Girard PL, et al: Processus expansifs intracraniens au Senegal.
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 7, 1979
Afr J Med Sci 4:143-159, 1973 17. Catane R, Kaufman J, West C, et al: Brain metastasis from prostatic carcinoma. Cancer 38:2583-2587, 1976 18. Kovi J, Heshmat MY: Incidence of cancer in Negroes in Washington, DC, and selected African cities. Am J Epidemiol 96:401-413, 1973 19. Dunham LJ, Bailar JC: World maps of cancer mortality rates and frequency ratios. J NatI Cancer Inst 41:155-203, 1968 20. Hou PG, Pang SC: Chorioepithelioma: Analytical study of 28 necropsied cases, with special reference to possibility of spontaneous retrogression. J Pathol Bacteriol 72:95-104, 1956 21. Junaid TA, Hendrickse JP, Oladiran B, et al: Choriocarcinoma in Ibadan, Nigeria: Epidemiologic aspects. J Natl Cancer Inst 53:1597-1602, 1974 22. Park WW, Less JC: Choriocarcinoma: General review, with analysis of 516 cases. Arch Pathol 49:73-104; 205-241, 1950 23. World Health Organization: Manual of the International Statistical Classificatior of Diseases, Injuries and Causes of Death, vof 1. Geneva, World Health Organization, 1967
673
A retrospective statistical analysis was done on metastatic brain tumors collected from two predominantly black hospitals in Washington, DC. A composite African series of metastatic brain tumors was also constructed for comparison. The results indicate that bronchogenic carcinoma is the predominant metastatic brain tumor (45.2 percent) among American blacks in Washington, DC, and chorioepithelioma, the most common (20.0 percent) among African blacks. In comparing these two series, much dissimilarity in the pattern of tumor distribution between these two genetically related ethnic groups suggests an important environmental role in the genesis of metastatic brain tumors. The present study also reveals a relatively high proportional frequency of prostatic carcinoma among metastatic brain tumors in blacks (3.8 percent in Washington, DC, and 2.1 percent in Africa).
The importance of a genetic role in the genesis of primary tumors in the central nervous system has been emphasized by previous authors through a statistical analysis of 17,035 cases of primary central nervous system tumors. I It clearly indicated that American blacks had a much higher frequency of meningioma and pituitary adenoma as compared to American Caucasians. A similar pattern of tumor distribution (proportional frequency) of various primary central nervous system tumors between American and African blacks was also demonstrated in that study. General information on metastatic brain tumors in predominantly white communities has been abundant in the literature.27 However, comparable information on metastatic brain Presented in part at the Eighth International Congress of Neuropathology, Washington, DC, September 27 1978. Requests for reprints should be addressed to Dr. Kuang-Jaw Fan, Department of Pathology, Howard University, College of Medicine, 520 W Street NW, Washington, DC 20059.
tumors in American blacks has not been substantially available. The purpose of this study is to elucidate the pattern of distribution of metastatic brain tumors in American blacks through a statistical analysis of accumulated material from two predominantly black hospitals in Washington, DC. An attempt is made also to compare these results with those of African blacks to determine whether genetic or environmental factors play a more important role in the genesis of metastatic brain tumors.
Materials and Methods Howard University Hospital and DC General Hospital are two predominantly black hospitals in Washington, DC. Traditionally, the great majority of patients in these two hospitals have been black. From 1954 to 1973, the departments of pathology in these two hospitals had diagnosed 306 cases of brain tumor, including necropsy and
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 7, 1979
surgical cases. Among them, 104 cases were metastatic. They were classified into subgroups (proportional frequency) according to primary site. A further analysis, according to age and sex distribution, was also made. The pattern of 'metastatic brain tumors (proportional frequency) in these two institutions was then contrasted to that of a composite African series. It was constructed from scattered published data on metastatic brain tumors from Uganda,8'0 Ivory Coast," Nigeria,'2 Kenya,'3"14 Zambia,'5 and Senegal.'6 All acceptable cases of metastatic brain tumors reported from 1953 to 1971 were
included. To avoid unnecessary confusion, only metastatic tumors found in the brain substance were included in this study. Tumors involving the epidural space or extending directly from adjacent structures were carefully excluded. Due to insufficient information on age and sex from African cases, further analysis of the composite African series was not possible. 671
Results Table 1 indicates that metastatic tumor was the most common tumor in the brain (34.0 percent) in these two predominantly black hospitals. Glioma, meningioma, and pituitary adenoma, in that order, were the three leading primary intracranial tumors, 25.8, 20.3, and 13.1 percent, respectively. When the metastatic brain tumors were
Table 1. Primary and Metastatic Brain Tumors by Histologic Type, Howard University and DC General Hospitals, 1954 to 1973 Tumor Type
Glioma Medulloblastoma Meningioma Pituitary adenoma Metastatic tumor Others Total
Case
%
79 7 62 40 104 14
25.8 2.3 20.3 13.1 34.0 4.6 100
306
classified into subgroups according to primary site (Table 2), it clearly was indicated that those of lung origin outnumbered the total of the other known primary sites. The second most common metastatic tumor was from breast (10.6 percent). Tumors from the kidney and prostate comprised 3.8 percent, each. When this series was compared to a composite African series, the patterns of tumor distribution (proportional frequency) differed greatly. The most common metastatic brain tumor in the African series was primary to the uterus (chorioepithelioma 20.0 percent). Tumors from the lung and breast comprised only 14.7 and 5.3 percent, respectively. In general, metastatic brain tumors in Africans were more diversely distributed from various primary sites as compared to those in Anmericans. In fact, approximately 30 percent of metastatic tumors rose from the skin (melanomna), soft tissue, liver, GI tract, and nasopharynx in the composite African series. Metastatic brain tumors in the authors' series were tabulated according to sex and primary site (Table 3).
Table 2. Metastatic Brain Tumors by Primary Site, Howard University and DC General Series (1954-1973) and Composite African Series (1953-1971)*
ICD** Number
Primary Site
142 146-9, 160 151-154 155.0 157 162 163.0 170-1 172-3 174 181 183-4 185 188 189.0 190 193 194.0 199 200
Salivary gland Nasopharynx Gl tract Liver Pancreas Lung Pleura Soft tissue Skin (melanoma) Breast Uterus (chorioepthelioma) Ovary, etc Prostate Bladder Kidney Eye Thyroid gland Adrenal Unknown Lymphoma, etc Total
Howard DC General % Case 0 1 2 1 2 47 0 1 3 11 0 1 4 0 4 0 0 2 25 0 104
0.0 1.0 1.9 1.0 1.9 45.2 0.0 1.0 2.9 10.6 0.0 1.0 3.8 0.0 3.8 0.0 0.0 1.9 24.0 0.0 100
*As indicated in Materials and Methods number (International Classification of Diseases)23
**Classification 672
African Series % Case 1 4 6 6 0 14 1 5 7 5 19 2 2 1 2 1 3 0 14 2 95
1.1 4.2 6.3 6.3 0.0 14.7 1.1 5.3 7.4 5.3 20.0 2.1 2.1 1.1 2.1 1.1 3.2 0.0 14.7 2.1 100
The major source of metastatic brain tumor among males was lung (52.2 percent). The second most common primary sites were kidney and prostate, which comprised only 5.8 percent of metastatic brain tumors in males. In females, the breast and lung were the two most common primary sites and they each comprised 31.4 percent of metastatic brain tumors. Metastatic brain tumors were tabulated by sex and age (Table 4). The peak age group for metastatic brain tumors in both sexes was 50 to 59 years. However, such tumors were more evenly distributed among various age groups in the female. In fact, the relative frequency of metastatic brain tumors among the age group, 30 to 49, was much higher in the female than the male sample.
Discussion The pattern of distribution (proportional frequency) of various metastatic brain tumors in both series generally reflected the relative frequency of the individual tumor at its primary site. However, it should be mentioned that metastatic brain tumor of prostate origin in these two series was much more common than general belief (3.8 percent in Washington, DC, and 2.1 percent in Africa). It has been stated that prostatic carcinoma rarely or never metastasizes to brain substance.7 A recent report of a literature review indicated that only 0.8 percent of metastatic brain tumors (ten of 1,202 cases) were from the prostate.'7 Although the relatively high frequency of prostatic carcinoma among metastatic brain tumors in our series was in line with the high incidence of prostatic carcinoma in the black population of Washington, DC,18 the frequency of this tumor to metastasize to the brain was still considered to be relatively low as compared to that of bronchogenic carcinoma. Prostatic carcinoma was shown to be slightly more common than bronchogenic carcinoma among males in Washington, DC. 18 In the composite Africian series, chorioepithelioma outnumbered bronchogenic carcinoma as the most common metastatic brain tumor. This result was apparently due to the high inci-
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 7, 1979
dence of chorioepithelioma in Africa and the high tendency of this tumor to metastasize to the brain.'1922 The importance of a genetic role in the genesis of primary brain tumors was suggested previously through a comparison of primary brain tumors between American and African blacks. ' It clearly indicated a similarity of tumor distribution (proportional frequency) of primary brain tumors between the two genetically and closely related ethnic groups. In contrast, a much different pattern of tumor distribution of metastatic brain tumors between the two ethnic groups indicated in this study perhaps emphasizes the importance of non-genetic factors in the development of metastatic brain tumors. Since the brain substance is well protected from the physical environment by a rigid skull, and the rather unique blood-brain barrier keeps the brain substance from being exposed to many noxious chemical agents circulating in the blood, it is conceivable that environmental factors play a less important role in the genesis of primary intracranial tumors than in that of extracranial tumors. These data, in conjunction with those from a previous study,' suggest that the genesis of metastatic brain tumors is influenced more by indirect environmental factors than by genetic factors.
Table 3. Metastatic Brain Tumors by Sex and Primary Site, Howard University and DC General Hospitals, 1954 to 1973 ICD Number 146-9, 160 151-154 155.0 157 162 170-1 172-3 174 183-4 185 189.0 194.0 199
Primary Site
Male
Nasopharynx Gl tract Liver Pancreas Lung Soft tissue Skin (melanoma) Breast Ovary, etc Prostate Kidney Adrenal Unknown Total
Case
%
1 1 1 1 36 0 2 0 0 4 4 2 18 69
1.5 1.5 1.5 1.5 52.2 0.0 2.9 0.0 0.0 5.8 5.8 2.9 26.1 100
Female Case % 0 1 0 1 11 1 1 11 1 0 0 0 7 35
0.0 2.9 0.0 2.9 31.4 2.9 2.9 31.4 2.9 0.0 0.0 0.0 25.7 100
Table 4. Metastatic Brain Tumors by Age and Sex, Howard University and DC General Hospitals, 1954 to 1973
Age 0-9 30-39 40-49 50-59 60-69 70-
Unknown Total
Case
Male
3 4 10 30 14 6 2 69
%Case% 4.3 5.8 14.5 43.5 20.3 8.6 2.9 100
0 5 8 10 6 3 3 35
Female 0.0 14.3 22.9 28.6 17.1
8.6 8.6 100
Acknowledgement The authors thank Dr. Sophie Perry for providing material from DC General Hospital.
Literature Cited 1. Fan KJ, Kovi J, Earle KM: The ethnic distribution of primary central nervous system tumors: Armed Forces Institute of Pathology, 1958 to 1970. J Neuropathol Exp Neurol 36:4149, 1977 2. Earle KM: Metastatic brain tumors. Dis Nerv Syst 16:86-92, 1955 3. Kernohan JW, Sayre GP: Tumors of the central nervous system, In: Atlas of Tumor Pathology, Fasc. 35. Washington, DC, Armed Forces Institute of Pathology, 1952, pp 17-58 4. Meyer PC, Reah TG: Secondary neoplasms of the central nervous system and meninges. Br J Cancer 7:438-448, 1953 5. Rubinstein LJ: Tumors of the central nervous system. In: Atlas of Tumor Pathology, series 2. Fasc. 6, Washington, DC, Armed Forces Institute of Pathology, 1972, pp 313-332 6. Russel DS, Rubinstein LJ: Pathology of Tumours of the Central Nervous System, ed 3. London, Edward Arnold, 1971, pp 261-272 7. Willis RA: Secondary tumors. In Minckler J (ed): Pathology of the Nervous System, vol 2. New York, McGraw-Hill, 1971, pp
2178-2196 8. Bailey IC: The pattern and presentation of intracranial tumors in Uganda. East Afr Med J 48:565-575, 1971 9. Billinghurst JR: Intracranial spaceoccupying lesions in African patients at Mulago Hospital, Kampala. East Afr Med J 43:385-393, 1966 10. Templeton AC: Tumours of the brain: Recent results. Cancer Res 41:200-202, 1973 11. Giordano C: Tumeurs du systeme nerveux en Cote d'lvoire. Afr J Med Sci 4:197-207, 1973 12. Odeku EL, Osuntokun BO, Williams AO: Tumors of the brain and its coverings: An African series. Int Surg 57:798-801, 1972 13. Kasili EG, Cameron HM, Ruberti RF, et al: Histopathology of brain tumors in the African in Kenya. Afr J Med Sci 4:99-106, 1973 14. Ruberti RF, Poppi M: Tumours of the central nervous system in the African. East Afr Med J 48:576-584, 1971 15. Chuke PO. Mathew TM, Naik GG: Tumours of the central nervous system in Zambia. Afr J Med Sci 4:107-110, 1973 16. Collomb H, Quenum C, Girard PL, et al: Processus expansifs intracraniens au Senegal.
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 7, 1979
Afr J Med Sci 4:143-159, 1973 17. Catane R, Kaufman J, West C, et al: Brain metastasis from prostatic carcinoma. Cancer 38:2583-2587, 1976 18. Kovi J, Heshmat MY: Incidence of cancer in Negroes in Washington, DC, and selected African cities. Am J Epidemiol 96:401-413, 1973 19. Dunham LJ, Bailar JC: World maps of cancer mortality rates and frequency ratios. J NatI Cancer Inst 41:155-203, 1968 20. Hou PG, Pang SC: Chorioepithelioma: Analytical study of 28 necropsied cases, with special reference to possibility of spontaneous retrogression. J Pathol Bacteriol 72:95-104, 1956 21. Junaid TA, Hendrickse JP, Oladiran B, et al: Choriocarcinoma in Ibadan, Nigeria: Epidemiologic aspects. J Natl Cancer Inst 53:1597-1602, 1974 22. Park WW, Less JC: Choriocarcinoma: General review, with analysis of 516 cases. Arch Pathol 49:73-104; 205-241, 1950 23. World Health Organization: Manual of the International Statistical Classificatior of Diseases, Injuries and Causes of Death, vof 1. Geneva, World Health Organization, 1967
673
