Effect of lycopene on prostate cancer among native African men: A protocol for an open-label randomized clinical trial in Tanzania

Study design and setting

This study will be a randomized phase III clinical trial of men diagnosed with PCa in Tanzania. The study will be conducted at two tertiary care facilities: the Kilimanjaro Christian Medical Center (KCMC) in Moshi, northern Tanzania, and the Ocean Road Cancer Institute (ORCI) in Dar es Salaam, Eastern Tanzania. KCMC is a tertiary, referral, and teaching hospital with a 640-bed capacity that provides medical services to a population of 15.7 million people and receives 268 patients with PCa per year.¹⁷ ORCI is the National Cancer Treatment Center for Tanzania, which receives patients from different parts of the country, with a bed capacity of 270 patients.

Interventions

The intervention arm will include PCa patients on standard treatment, such as radical prostatectomy or radical radiotherapy, and hormonal manipulation such as bilateral total orchidectomy, medical castration, or chemotherapy for advanced disease, in addition to tomato paste as an intervention. During clinic attendance, these men will be asked to take one sachet (60 g of tomato paste) daily. The tomato paste will be locally purchased, produced by a licenced Redgold factory in the Arusha region, northern Tanzania, and verified and certified by the Tanzania Food and Drug Authorities. Tomato paste consumption will be evaluated on three consecutive visits: three, six, and 12 months after randomization. The baseline serum concentration of lycopene was measured at the Kilimanjaro Clinical Research Institute (KCRI) laboratory in Tanzania. The Men will be asked to consume tomato paste either alone or mixed with food and not cooked to avoid exposure to more heat. The control arm will receive standard treatment according to national guidelines.

Study population

The sample size was calculated using the following formula for comparison of means between the two groups: $2{\mathit{SD}}^2{\left(Z_{a/2}+Z_b\right)}^2/d^2.$¹⁸ The study will enroll 400 men diagnosed with prostate cancer, confirmed by histopathology, with PSA of 4 ng/ml or greater, attending KCMC and ORCI, and will provide informed consent. Men will be randomized in a 1:1 ratio using computer-generated allocation, seal envelope approach to receive an intervention (200 men) and a control/standard treatment (200 men), equally allocated across sites, and followed for 12 months, taking equal numbers at each site. The randomization will be performed by an experienced clinical trial statistician and allocation performed by trained residents of the study team from the two study sites. The study will exclude patients with chronic gastrointestinal (GI) symptoms, since the study involves ingestion of a nutrient, malabsorption, diarrhea, allergy to tomato products, and critically ill patients.

Standard operating procedures

At baseline, consenting participants will be screened for demographic and clinical characteristics, total PSA, serum lycopene, and histopathology. PCa staging will be performed using digital rectal examination, assessment of symptoms, and physical examination. The Gleason scores for the level of apoptosis were determined by a pathologist. Trained clinicians will collect data using a questionnaire. Follow-up will be done at three, six and 12 months for the assessment of PSA, urinary symptoms, quality of life, and experience with tomato paste consumption. Histopathological examination was performed to examine and quantify apoptosis in the prostate gland before and after lycopene therapy. Reduction in PSA level, assessment of disease progression by ECOG, and Gleason score will also be measured at each visit. At each visit, we will examine serum lycopene, PSA, and clinical evaluations, such as blood pressure and physical examination, to assess comorbidities except for a trucut biopsy, which will be repeated after one year for histopathology. A dose of 48 mg lycopene/100 g of tomato paste has been documented elsewhere¹⁹; however, we tested the concentration of lycopene in our local tomato paste.

Measures

PSA levels will be tested using the MAGLUMI 2000 Snibe Diagnostic tool from ABBOTT AIDD Longford, Ireland. The reaction was tested using a MAGLUMI total PSA chemiluminescence immunoassay (CLIA) cartridge containing magnetic microbeads, high and low calibrators buffer (ABEI Label), and diluent. To ensure proper test performance, we strictly adhered to the operating instructions of the fully auto-CLIA analyzer MAGLUMI. Each test parameter was identified via an RFID tag on the Reagent Integral. We used 300ul of serum sample in the sample chamber. The PSA results will be reported in terms of concentration (ng/ml). Samples with concentrations above the measurement range were diluted manually or using an analyzer. After manual dilution, the result was multiplied by the dilution factor. The analyzer software then automatically considered the dilution when calculating the sample concentration.

The central focus of this study was to examine serum lycopene levels using UV-high-performance Liquid Chromatography (HPLC) analysis. This method entails the extraction of lycopene from serum using the protein crushing technique, employing ethanol, ascorbic acid, and hexane. The subsequent analysis will be conducted under isocratic conditions using the 3000 Ultimate Dionex and a C18 column (Hypersil 5-19626:150 × 4.6 mm i.d., 5 μm particle)^20,21 within the facilities of the KCRI-biotechnology laboratory. At 12 months, a trucut biopsy was repeated for histological evaluation by a pathologist, focusing on Gleason’s score to assess disease progression. Additionally, mobile phone follow-ups will be conducted weekly to assess whether participants are taking the tomato paste (intervention) or following the standard treatment, have experienced complications, and assess the overall improvement of their health. Any reported adverse effects will be recorded in the adverse effect report form at each visit and any phone call follow-ups.

Data collection

Trained resident doctors collected data using a structured questionnaire with the REDCap software. The tool will be in English and will be administered in Kiswahili, the local language. At each visit, 5 mls of venous blood was collected from participants for PSA and serum lycopene testing. Clinical assessment will be performed to assess urinary symptoms, experience with tomato consumption, and quality of life. The study will refund transport fares for all study participants. All information about the participants will be kept confidential and accessible only to the trial team. The trial committee will be responsible for checking the protocol for its completeness. The trial sponsor is responsible for auditing the trial.

Data analysis

Data cleaning and analysis were performed using the Stata version 15 software. Data analysis was performed based on the intention to treat (ITT) principle. Descriptive statistics were used to compare average lycopene and PSA levels in the intervention group using T-test and Chi-squared tests. Generalized linear mixed models will further assess the effects of lycopene on PCa progression, urinary symptoms, and PSA reduction. Model performance will be assessed using the Akaike Information Criteria, and all analyses will be assessed at a 5% threshold level. Multiple imputation techniques were used for the analysis of missing data. All statistical tests were two-sided at an alpha level of <0.05.