In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

[Q]: Context: Most solid human tumors exist in an acidic microenvironment, due in part to inefficient vasculature and a higher intrinsic rate of glycolysis. This leads to a tumor-selective pH gradient, which can be exploited therapeutically with antitumor agents such as the camptothecins (CPTs). Previous work in this laboratory has shown that camptothecin activity is enhanced 40- to 60-fold in monolayer cell culture by reducing the extracellular pH to 6.8. Three-dimensional histoculture has been shown to be a technique that allows human tumor tissue to grow in an in vivo-like way with maintenance of tissue histology and function and drug sensitivity for long periods of time.', 'In the current study, we utilized these features of histoculture to study new analogues of camptothecin that have superior pharmacological properties.', 'We evaluated six CPT analogues in histocultures of human brain, neuroblastoma, breast, colon, and prostate tumors. Fragments were exposed to 10,11-methylenedioxy-CPT (MDC), 7-chloromethyl-MDC, SN-38, topotecan (TPT), 9-amino-CPT, 10-amino-CPT, paclitaxel, 5-fluorouracil, 4-hydroperoxycyclophosphamide and doxorubicin, and antitumor activity was assessed. For in vivo tumor outgrowth studies, fragments were treated in parallel, implanted into nude mice, and monitored for development of tumors. RESULTS. Against 15 of 16 tumor xenografts and all primary tumor samples tested, all compounds were cytotoxic at pH 7.4 (IC(50) range 13-921 microM). MDC, SN-38, TPT, and 9-amino-CPT achieved an average 5-fold increase in activity (range 3-14) at pH 6.8, while 7-chloromethyl-MDC was enhanced 8-fold (range 6-14). The most potentiated analogue was 10-amino-CPT at 27-fold (range 17-49). In contrast, the other agents were active against one or more tumor types but were not enhanced by acidic pH. Importantly, the toxicity of MDC in histoculture of D54 glioma xenografts strongly correlated with the outgrowth of treated fragments subsequently implanted in vivo.\Question: Is the activity of camptothecin analogues enhanced in histocultures of human tumors and human tumor xenografts by modulation of extracellular pH?
[A]: Evaluation of anticancer drug activity in native-state histoculture supports the concept that pH modulation may be an important approach to improve the selectivity and antitumor effectiveness of camptothecin-based chemotherapy.


[Q]: Context: To investigate the prognostic value of the pre-treatment haemoglobin level in patients with advanced squamous cell head and neck cancer treated with induction polychemotherapy.', 'Seventy-two patients with advanced squamous cell head and neck cancer received primary combination chemotherapy consisting of docetaxel 75 mg/m(2) on day 1, cisplatin 100 mg/m(2) on day 1, and 5-fluorouracil (5-FU) 1000 mg/m(2)/day on days 1-4 (total dose 4000 mg/m(2)), repeated on days 1, 22 and 43 followed by chemoradiation. The data collected included pre-treatment haemoglobin, response to treatment, disease-free and overall survival.', 'The pre-treatment haemoglobin level was found to be a significant predictor of response to induction chemotherapy (P = 0.01) and an independent predictor of overall survival [hazard ratio (HR) 0.77, 95% confidence interval (CI) 0.58-1.03, P = 0.0001] and disease free survival (HR 2.09, 95% CI 1.41-3.09, P = 0.0001). Furthermore N-stage was found to be a significant prognostic factor of overall survival (HR 9.24, 95% CI 6.90-21.34, P = 0.005). The Eastern Cooperative Oncology Group performance status scale was also found to be significant for disease free survival (HR 7.66, 95% CI 2.61-22.46, P = 0.003).\Question: Does pre-treatment haemoglobin level predict response and survival after TPF induction polychemotherapy in advanced head and neck cancer patients?
[A]: In patients with advanced squamous cell head and neck cancer, the haemoglobin level prior to induction chemotherapy is significantly related to outcome including response and survival.


[Q]: Context: Decisions involving risk often must be made under stressful circumstances. Research on behavioral and brain differences in stress responses suggest that stress might have different effects on risk taking in males and females.', 'In this study, participants played a computer game designed to measure risk taking (the Balloon Analogue Risk Task) fifteen minutes after completing a stress challenge or control task. Stress increased risk taking among men but decreased it among women.\Question: Does acute stress increase sex differences in risk seeking in the balloon analogue risk task?
[A]:
Acute stress amplifies sex differences in risk seeking; making women more risk avoidant and men more risk seeking. Evolutionary principles may explain these stress-induced sex differences in risk taking behavior.