A detailed prospective study of 58 consecutive breast cancer patients and contemporaneous controls, using age, duration of tumour and presence or absence of poor prognostic signs as clinical parameters, clearly showed that the patients fell into three distinct groups. Group A accounted for 30 per cent of cancers and consisted of young women (21-45 years) with advanced cancers, a short history (3 months or less) and poor prognostic signs; these patients had fast-growing tumours. Group B, to which nearly 60 per cent of patients belonged, was made up of menopausal women (46-50 years) with advanced disease, a history of from 3 months to 1 year and poor prognostic signs; their tumour growth rate was intermediate. Group C made up slightly more than 10 per cent of cases and consisted of postmenopausal women (50 years and above) who gave a long history (1 year or more), and had resectable tumours without poor prognostic signs. Thus, although advanced breast cancer in tropical Africa is due to late presentation in the majority of cases, a small but significant proportion of women have advanced disease in spite of early presentation, attributable to fast tumour growth rate.
In this study, we investigate the extent to which infrastructure development affects economic performance in Africa. To pick up the economy-wide effects and possible feedback mechanism from network externalities, we jointly estimate a system of equations that endogenizes the relationship between infrastructure demand and supply with an aggregate output equation, using nonlinear 3SLS-GMM techniques. We find causal evidence of a significant positive link between infrastructure development and economic growth, especially for transport infrastructure. We also find evidence of infrastructure’s increasing returns to growth, with the strongest growth potential materializing after a critical mass of infrastructure has been built and network externalities kick in. One policy implication from our findings is that it is “big-push” and not marginal infrastructure improvements that are required to attain a critical mass, kick start network externalities, and fully unlock infrastructure’s growth potential for the continent. Our results reinforce the case for regional infrastructure integration in Africa.
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