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Objective:To compare the setup errors between deep inspiration breath hold (DIBH) and free breathing (FB) for breast cancer patients who were treated with whole breast irradiation (WBI) after breast conserving surgery (BCS).Methods:In this retrospective analysis, 30 breast cancer patients receiving WBI following BCS using DIBH in National Cancer Center/ Chinese Academy of Medical Sciences, an 30 patients treated with WBI using FB were enrolled as comparator.The kilovoltage cone-beam computed tomography (CBCT) was performed to evaluate and reduce setup errors. The optimal margins from clinical target volume (CTV) to planning target volume (PTV) for DIBH were estimated. The differences of setup errors between two techniques were compared using independent two-sample t-test. Results:A total of 318 sets of CBCT images were acquired, with (5.1±1.1) sets per patient on average. The setup errors along the three translational directions (laternal, longitudinal and vertical) were (2.1±1.6) mm, (2.6±1.7) mm and (2.5±2.1) mm for DIBH, and (2.2±1.7) mm, (3.1±2.5) mm and (3.3±2.3) mm for FB, respectively. Compared with FB, DIBH significantly reduced setup errors in the longitudinal ( P=0.015) and vertical ( P=0.004) directions, whereas the setup errors in the lateral direction did not significantly differ ( P=0.294). The optimal margins from CTV to PTV using DIBH were 6.2 mm, 7.3 mm and 7.8 mm, respectively. In the DIBH group, treatment fractions at the beginning and higher body mass index (BMI) did not associate with larger set-up deviation. Conclusions:DIBH technique yields less setup errors than FB for breast cancer patients treated with WBI after BCS. The CTV-PTV margins of 6-8 mm are recommended for DIBH.
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Objective:To analyze the efficacy of chest wall boost radiotherapy in stage T 4 breast cancer patients after modified radical mastectomy. Methods:A retrospective analysis was performed on the data of 148 stage T 4 breast cancer patients who were admitted from 2000 to 2016 and received radiotherapy after modified radical mastectomy. There were 57 cases in the chest wall boost radiotherapy group and 91 cases in the conventional dose group. Radiotherapy was performed by conventional+ chest wall electron beam, three-dimensional conformal+ chest wall electron beam, intensity modulated radiotherapy+ chest wall electron beam irradiation. EQD 2 at the boost group was >50Gy. All patients received neoadjuvant chemotherapy. Kaplan-Meier method was used to analyze survival; Logrank was used to test differences; and Cox model was used to do multivariate prognostic analysis. Results:The median follow-up time was 67.2 months. The 5-year rates of chest wall recurrence (CWR), locoregional recurrence (LRR), disease-free survival (DFS), and overall survival (OS) were 9.9%, 16.2%, 58.0%, and 71.4%, respectively. The 5-year rates of CWR, LRR, DFS, and OS with and without chest wall boost radiotherapy were 14% vs. 7%, 18% vs. 15%, 57% vs. 58%, 82% vs. 65%( P>0.05), respectively. Multivariate analysis showed that chest wall boost radiotherapy had no significant effect on prognosis ( P>0.05). Among 45 patients in the recurrent high-risk group, boost radiotherapy seemed to have higher OS rate ( P=0.058), DFS rate ( P=0.084), and lower LRR rate ( P=0.059). Conclusions:Stage T 4 breast cancer patients had strong heterogeneity. Chest wall boost radiotherapy did not apparently benefit all patients. For patients with 2-3 high risk factors including positive vascular tumor embolus, pN 2-N 3, and hormone receptor negative, chest wall boost radiotherapy showed a trend of improving efficacy.
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Objective To analyze the failure patterns of locoregional recurrence (LRR) and investigate the range of radiotherapy in T1-2N1 breast cancer patients undergoing modified radical mastectomy.Methods From September 1997 to April 2015,2472 women with T1-2N1 breast cancer after modified radical mastectomy without neoadjuvant systemic therapy were treated in our hospital.1898 patients who did not undergo adjuvant radiotherapy were included in this study.The distribution of accumulated LRR was analyzed.The LR and RR rates were estimated by the Kaplan-Meier method,and the prognostic factors were identified in univariate analyses with Log-rank test.Multivariate analysis was performed using Cox logistic regression analysis.Results With a median follow-up of 71.3 months (range 1.1-194.6),164 patients had LRR,including supraclavicular/infraclavicular lymph nodes in 106(65％),chest wall in 69(42％),axilla in 39(24％) and internal mammary lymph nodes (IMNs) in 19 patients (12％).In multivariate analysis,age (＞45 years vs.≤45 years),tumor location (other quadrants vs.inner quadrant),T stage (T1 vs.T2),the number of positive axillary lymph nodes (1 vs.2-3),hormone receptor status (positive vs.negative) were significant prognostic factors for both LR and RR.Conclusions In patients with T1-2N1 breast cancer after modified radical mastectomy,the most common LRR site is supraclavicular/infraclavicular nodal region,followed by chest wall.The axillary or IMN recurrence is rare.The prognostic factors for LR and RR are similar,which indicates that supraclavicular/infraclavicular and chest wall irradiation should be considered for postmastectomy radiotherapy.
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Objective@#To analyze the failure patterns of locoregional recurrence (LRR) and investigate the range of radiotherapy in T1-2N1 breast cancer patients undergoing modified radical mastectomy.@*Methods@#From September 1997 to April 2015, 2472 women with T1-2N1 breast cancer after modified radical mastectomy without neoadjuvant systemic therapy were treated in our hospital. 1898 patients who did not undergo adjuvant radiotherapy were included in this study. The distribution of accumulated LRR was analyzed. The LR and RR rates were estimated by the Kaplan-Meier method, and the prognostic factors were identified in univariate analyses with Log-rank test. Multivariate analysis was performed using Cox logistic regression analysis.@*Results@#With a median follow-up of 71.3 months (range 1.1-194.6), 164 patients had LRR, including supraclavicular/infraclavicular lymph nodes in 106(65%), chest wall in 69(42%), axilla in 39(24%) and internal mammary lymph nodes (IMNs) in 19 patients (12%). In multivariate analysis, age (>45 years vs.≤45 years), tumor location (other quadrants vs. inner quadrant), T stage (T1 vs. T2), the number of positive axillary lymph nodes (1 vs. 2-3), hormone receptor status (positive vs. negative) were significant prognostic factors for both LR and RR.@*Conclusions@#In patients with T1-2N1 breast cancer after modified radical mastectomy, the most common LRR site is supraclavicular/infraclavicular nodal region, followed by chest wall. The axillary or IMN recurrence is rare. The prognostic factors for LR and RR are similar, which indicates that supraclavicular/infraclavicular and chest wall irradiation should be considered for postmastectomy radiotherapy.
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Objective@#To validate whether the prognostic stage groups by the 8th edition of the American Joint Committee on Cancer (AJCC) staging system provides improved prognostic accuracy in T1-2N1M0 postmastectomy breast cancer patients compared to 7th edition.@*Methods@#a total of 1 823 female patients with T1-2N1M0 breast cancer who underwent mastectomy and axillary lymph node dissection without neoadjuvant chemotherapy were analyzed and restaged according to 8th edition. Univariate analysis of prognostic factors was evaluated by using log-rank test. Multivariate analysis was estimated by using the Cox proportional hazards model. The prognostic accuracy of the two staging systems was compared using receiver operating characteristic (ROC) analyses and the concordance index (C-index).@*Results@#5-year locoregional recurrence rate (LRR) for the whole group was 6.0%, 5-year distant metastasis (DM) rate was 11.5%, 5-year disease-free survival (DFS) was 85.0%, and 5-year overall survival (OS) was 93.1%. Cox analysis showed that 7th edition of the AJCC staging system and progesterone receptor status were independent risk factors for LRR, DM, DFS and OS (P<0.05). Compared with stage by 7th edition, 1 278(70.1%) were assigned to a different prognostic stage group: 1 088 (85.1%) to a lower stage and 190 (14.9%) to a higher stage. LRR, DM, DFS and OS were significantly different between prognostic stage ⅠA, ⅠB, ⅡA, ⅡB and ⅢA according to 8th edition of the AJCC staging system(P<0.001). Prognostic stage had significantly higher C-indexes and provided better estimation of prognosis compared to stage by 7th edition of the AJCC staging system (P<0.001).@*Conclusion@#The prognostic stage groups of 8th edition AJCC staging system has superior prognostic accuracy compared to 7th edition in T1-2N1M0 breast cancer, and has better clinical therapeutic guidance value.
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Objective@#To investigate the dose characteristics and outcomes of a single isocenter bilateral tangential fields (IBTF) combined with intensity-modulated radiotherapy (IMRT) in bilateral breast radiotherapy (BBR).@*Methods@#Fourteen female patients with synchronous bilateral breast cancer (SBBC) after breast-conserving surgery (BCS) were enrolled in this study. All patients received BBR using IBTF combined with IMRT at a conventional (50 Gy/25f) or hypofractionated (43.5 Gy/15f) dose. For patients with invasive cancer, the additional tumor bed boost was given with sequential electron radiation or simultaneously photon IMRT. The coverage, uniformity and short-term clinical efficacy were evaluated.@*Results@#The number of the irradiation field was 8-11, including 4-7 intensity-modulated fields. The bilateral breast PTV dose coverage reached 95% in all plans. For the tumor bed, the mean dose coverage was (95.54±1.33)%(left) and (94.19±1.03)%(right) using photon, and (90.25±8.79)%(left) and (85.28±8.35)%(right) using electron. The average V20 of bilateral lungs was (16.69±3.90)%. The cardiac Dmean was 5.48 Gy. Three patients presented with grade Ⅱ acute skin toxicities. No ≥ grade Ⅱ pneumonitis was observed. No recurrence occurred with the median follow-up time of 30.1 months. Eleven patients showed excellent cosmetic results.@*Conclusion@#BBR using IBTF combined with IMRT is efficacious and safe for patients with SBBC after BCS.
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Objective To quantify the setup errors measured with kV cone-beam CT (CBCT) using breast board with or without a thermoplastic head mask in breast cancer patients who received whole breast and supraclavicular nodal region irradiation.Clinical target volume (CTV) to planning target volume (PTV) in 3 directions were also calculated.Methods The study included thirty patient receiving both whole breast and supraclavicular nodal region irradiation on Elekta Versa HD linear accelerators (Elekta Oncology Systems,Crawley,UK) between June 2016 and January 2018.The setup error data were retrospectively analyzed.All the patients were immobilized in the supine position on a breast board system (Carbon fibre breast board,Civco,Iowa,USA) with both arms raised.Twenty of the patients added an extra thermoplastic head mask to immobilize the neck.A CBCT scan was taken before treatment at the first 3 to 5 fractions and then once every week.Registration with the planning CT was performed and adjusted to match the target volume of the supraclavicular nodal region and the cervical vertebra by experienced medical staff,the position of the arms and the breast were also considered.For all patients the couch shifts in left-right (x),superior-inferior (y),anterior-posterior (z) were recorded.Statistical analysis included two-tails significance tests (t-Student and Manne-Whitney test for means,x2 test for variances).Population of the two groups was compared in terms of distribution of the mean shift (systematic error) and their standard deviations (random error).Van Herk's setup margin defined as MPTV =2.5Σ + 0.7δ was calculated in patients with or without mask immobilization.Results Altogether,56 images and 109 images were acquired in breast board only group and head mask group,respectively.Shifts of the breast board only group and the head mask group in x,y,z were 0.212±0.174 cm vs.0.272±0.242 cm (P=0.070);0.364±0.246 cm vs.0.242±0.171 cm (P=0.001);0.423±0.302 cm vs.0.364±0.269 cm (P=0.204).Proportion of the shift less than 5 mm in the breast board only group and the head mask group were 91.07％ vs.85.32％ (P=0.294);67.86％ vs.89.91％ (P=0.001);67.86％ vs.74.31％ (P=0.381).The CTV to PTV margin in x,y,z were 0.645 cm,0.981 cm,1.317 cm in breast board only group and 0.873 cm,0.709 cm,0.961 cm in head mask group,respectively.Setup error in the x direction was significantly correlated with BMI (P=0.001).Conclusions For the alignment and immobilization of patients who received whole breast and supraclavicular nodal region irradiation,using a breast board in combination of a thermoplastic head mask may significantly help to reduce the shift variance in superior-inferior direction compared to using breast board only.The anterior-posterior error is relatively large,other immobilization device or patient alignment methods are needed to be further explored to improve the accuracy.
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Objective To investigate the dose characteristics and outcomes of a single isocenter bilateral tangential fields (IBTF) combined with intensity-modulated radiotherapy (IMRT) in bilateral breast radiotherapy (BBR).Methods Fourteen female patients with synchronous bilateral breast cancer (SBBC) after breast-conserving surgery (BCS) were enrolled in this study.All patients received BBR using IBTF combined with IMRT at a conventional (50 Gy/25f) or hypofractionated (43.5 Gy/15f) dose.For patients with invasive cancer,the additional tumor bed boost was given with sequential electron radiation or simultaneously photon IMRT.The coverage,uniformity and short-term clinical efficacy were evaluated.Results The number of the irradiation field was 8-11,including 4-7 intensity-modulated fields.The bilateral breast PTV dose coverage reached 95％ in all plans.For the tumor bed,the mean dose coverage was (95.54± 1.33) ％ (left) and (94.19± 1.03) ％(right) using photon,and (90.25± 8.79) ％ (left) and (85.28± 8.35) ％(right) using electron.The average V20 of bilateral lungs was (16.69±3.90)％.The cardiac Dmean was 5.48 Gy.Three patients presented with grade Ⅱ acute skin toxicities.No ≥ grade Ⅱ pneumonitis was observed.No recurrence occurred with the median follow-up time of 30.1 months.Eleven patients showed excellent cosmetic results.Conclusion BBR using IBTF combined with IMRT is efficacious and safe for patients with SBBC after BCS.
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Objective To investigate the setup errors and influencing factors of the whole breast intensity-modulated radiotherapy (IMRT) after breast-conserving surgery,and to identify the margins from clinical target volume (CTV) to planning target volume (PTV).Methods Thirty patients with left-sided (n=15) or right-sided breast cancer (n=15) receiving whole breast hypofractionated IMRT with breast board immobilization after breast-conserving surgery in Cancer Hospital from 2016 to 2017 were enrolled.The kilo-voltage cone-beam computed tomography (CBCT) was used to compare the errors of planning CT and treatment unit and determine the setup errors.The margins from CTV to PTV were calculated.The setup errors under different conditions were statistically compared by t-test.Results A total of 151 sets of CBCT images were taken in the whole cohort,(5.0± 1.3) sets per patient on average.The setup errors in the x-axis (left-right direction),y-axis (cranial-caudal direction) and z-axis (anterior-posterior direction) were (2.2± 1.7) mm,(3.1±2.5) mm and (3.3±2.3) mm,respectively.The margins from CTV to PTV were 6.39 mm,10.00 mm and 8.57 mm,respectively.The setup error in anterior-posterior direction in the first week was (3.7±2.5) mm,significantly larger than (2.6±1.6) mm in the following week (P=0.002).The setup error of the patients with overweight or obesity was (3.9±2.6) mm,significantly higher than (2.9±2.0) mm in those with normal weight in the z-axis direction (P=0.033).Conclusion The margins from CTV to PTV are recommended to be ranged from 6 to 10 mm during hypofractionated whole breast IMRT with breast board immobilization after breast-conserving surgery.More frequent imaging verification should be applied in the first week of IMRT.
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Objective@#To investigate the overall efficacy of early breast cancer after breast-conserving treatment. To analyze risk factors affecting local regional recurrence (LRR), distant metastasis (DM) and survival.@*Methods@#1 791 breast cancer patients treated with breast-conserving surgery were retrospectively analyzed. The inclusion criteria were pathologic diagnosis of invasive breast cancer without supraclavicular and internal mammary node metastasis, T1-2N0-3M0, and no neoadjuvant therapy. Univariate analysis of survival was performed by Kaplan-Meier method and log rank test. Cox regression model was used for multivariate analysis.@*Results@#The median follow-up time was 4.2 years. For all patients, the 5-year LRR, DM, disease-free survival(DFS) and overall survival(OS) rates were 3.6%, 4.6%, 93.0% and 97.4%, respectively. The LRR rates of patients with Luminal A, Luminal B1, Luminal B2, HER-2 over-expressed and triple-negative breast cancer were 2.0%, 6.1%, 5.9%, 0 and 10.0%, while the DM rates were 3.2%, 6.7%, 8.3%, 4.8% and 7.3%, respectively. Among the N0 patients, axillary dissection was performed in 689 cases and sentinel lymph node biopsy in 652 cases. The 5-year LRR rates were 3.3% and 3.2% (P=0.859), and the OS rates were 98.2% and 98.3% (P=0.311) respectively, which showed no statistically significant. There were 1 576 patients that underwent postoperative radiotherapy. Postoperative radiotherapy significantly reduced the 5-year LRR compared with surgery alone (2.5% vs 12.9%). The 5-year LRR rates of patients who received conventional fractionated radiotherapy and hypo-fractionated radiotherapy were 2.7% and 3.1%, respectively. But the difference was not statistically significant (P=0.870). Multivariate analysis showed that age, lymphovascular invasion, pathological T staging, postoperative radiotherapy, ER/PR status and endocrine therapy were independent factors of LRR in breast cancer patients (all P<0.05). Histological grade and pathological N staging were independent factors of DM (all P<0.05). The age, lymphovascular invasion, pathological T and N staging, postoperative radiotherapy, ER/PR status and endocrine therapy were independent factors for DFS (all P<0.05). Histological grade, pathological N staging, ER/PR status and endocrine therapy were factors for OS (all P<0.05).@*Conclusions@#With contemporary standard treatment, the recurrence rate of early breast cancer after breast conserving treatment is less than 10%. Node-negative patients after sentinel lymph node biopsy did not need axillary dissection. The overall utilization of radiotherapy after breast conserving surgery is satisfactory. Hypofractionated radiotherapy is as effective as conventional fractionated radiotherapy. Local regional recurrence and distant metastasis have different risk factors.
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Objective@#To analyze the clinical features and prognosis of the ipsilateral breast tumor recurrence (IBTR) after breast conserving surgery.@*Methods@#From 1999 to 2013, 63 women with IBTR after breast conserving surgery were retrospectively reviewed. All patients had adequate information on tumor location both at first presentation and at recurrence, with or without regional recurrence or distant metastasis. The histologic changes between true local recurrence and elsewhere recurrence groups were compared. The local recurrence, the overall survival after IBTR (IBTR-OS), the disease-free survival after IBTR (IBTR-DFS) were also compared.@*Results@#All patients had undergone lumpectomy, including 38 cases with additional axillary lymph node dissection and 13 cases with sentinel lymph node biopsy. There were 11.3% (7/63) cases received neoadjuvant systemic therapy, 68.3% (43/63) had adjuvant radiotherapy, 60.3% (38/63) underwent adjuvant chemotherapy and 47.6% (30/63) received hormonal therapy. Forty-five cases (71.4%) had recurrence in the same quadrant, and 18 cases (28.6%) had elsewhere recurrence. Compared with histology at presentation, 10.3% of the patients (6/58) had different ones at recurrence and 28.9% of patients (13/45) had different molecular subtypes. The conversion rate of estrogen receptor status (33.3% vs 9.5%, P=0.012) and progesterone receptor status (56.3% vs 19.0%, P=0.005) in patients with elsewhere recurrence was significantly higher than that in patients with same quadrant recurrence. Fifty-nine cases had undergone surgery after IBTR, with 48 cases of secondary breast-conserving surgery and 11 cases of salvage mastectomy. The median time to IBTR of same quadrant recurrence and elsewhere recurrence groups were 26 months and 62 months (P=0.012), respectively. There were 84.4% and 44.4% cases who had local recurrence within 5 years after breast conserving surgery, respectively. Of all cases, the overall 5-year IBTR-OS and 5-year IBTR-DFS rates were 79.4% and 60.4%, respectively. There were no significant differences in 5-year IBTR-OS (77.4% vs. 83.6%, P=0.303) or 5-year IBTR-DFS (60.0% vs. 62.8%, P=0.780) between same quadrant recurrence and elsewhere recurrence groups. Univariate analysis showed that pN0-1 (P<0.001), luminal subtype (P=0.026), adjuvant endocrine therapy (P=0.007) at first presentation, recurrent tumor < 3 cm (P=0.036) and having surgery after IBTR(P=0.002) were favorable factors of IBTR-OS. pN0-1 (P<0.001) at first presentation, recurrent tumor stage Ⅰ-Ⅱ (P<0.001) and having surgery after IBTR(P=0.001) were favorable factors of IBTR-DFS. There was no significant difference between second breast-conserving surgery and salvage mastectomy in IBTR-OS and IBTR-DFS (P>0.05).@*Conclusions@#The IBTR after breast conserving surgery mainly occurred at the original quadrant. Second breast-conserving surgery did not affect patient′s prognosis. There were significant differences in biological features between the same quadrant recurrence and elsewhere recurrence, requiring different therapeutic strategies in the future.
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Objective To analyze the correlation between treatment time and radiotherapy plan of deep inspiration breath-hold (DIBH) technique for the whole breast irradiation (WBI) in the left breast cancer after breast-conserving surgery,verify the inter-fractional reproducibility of radiotherapy,observe the heart location and dosimetric changes and calculate the effect of DIBH upon the WBI setup error after the surgery.Methods We prospectively enrolled 15 patients with left breast cancer undergoing WBI after breast-conserving surgery,who met the requirement of D1BH.Treatment time was recorded,its correlation with the number of field and monitor unit was analyzed.Inter-fractional setup errors and PTV delineation were calculated using cone beam CT (CBCT).The accuracy of the position and dose of the heart during radiotherapy was verified by the imaging fusion of CBCT and CT images.The variables among groups were analyzed by non-parametric Firedman test.Results The average treatment time of DIBH radiotherapy was 4.6 minutes.The treatment time was correlated with the maximal and total number of sub-fields and total monitor units.During DIBH treatment,the mean cardiac displacement volume was 19.1 cm3(3.8％).The mean cardiac dose difference between CBCT and planning CT was 5.1 cGy,and there was no significant difference in the heart V5-V30.The mean inter-fractional system setup error (∑) and random setup error (σ) in the left-right (x),superior-inferior (y) and anterior-posterior (z) direction were ∑x 1.9 mm,∑y 2.1 mm,∑z 2.0 mm,σx 1.3 mm,σy 1.3 mm,σz 1.4 mm,respectively.The corresponding minimal margins for setup error were 5.7 mm,6.2 mm and 6.0 mm,respectively.Conclusion DIBH for WBI after breast-conserving surgery does not significantly prolong the treatment time.Treatment time is related to treatment plan.DIBH yields high inter-fractional reproducibility and protects the heart.
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Objective To study the effect of deep inspiration breath-hold(DIBH)technique on the heart dose in whole breast irradiation(WBI)for left breast cancer after breast-conserving surgery, and to investigate the anatomical factors for heart dose. Methods Fifteen patients with left breast cancer who received WBI after breast-conserving surgery and met breathing control requirements were prospectively enrolled as subjects. Simulated CT scans were performed during free breathing(FB)and DIBH. The WBI plans were optimized based on DIBH images.The position,volume,and radiation doses to the heart and lung were compared between the status of FB and DIBH. Correlation of heart dose with various anatomical factors was analyzed in FB status. Between-group comparison of categorical data was made by nonparametric Wilcoxon rank test.A two-variable correlation analysis was made by the Pearson method.Results There was no significant difference in heart volume between the status of FB and DIBH(P=0.773).The volume of both lungs was significantly larger in DIBH status than in FB status(P=0.001). The mean and maximum doses and V5-V40for the heart,left anterior descending coronary artery,left ventricle,right ventricle,and left lung were significantly lower in DIBH status than in FB status(all P<0.05). The greater DIBH increased the lung volume,the greater the mean heart dose decreased. In FB status,the left breast volume,heart-to-lung volume ratio,distance between the inferior margins of breast and heart,and maximum heart margin distance showed a linear correlation with heart dose. Particularly, the heart-to-lung volume ratio and maximum heart margin distance were independently correlated with heart dose. Conclusions DIBH technique in WBI for left breast cancer after breast-conserving surgery significantly reduces heart and lung doses compared with FB. Changes in lung volume are the basis for improving the relative anatomical location of the heart. The heart-to-lung volume ratio and maximum heart margin distance may provide a reference for DIBH technique.
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Radiotherapy is an essential part of postoperative adjuvant therapy for breast cancer.However,postoperative radiotherapy for breast cancer poses a potential risk of heart damage.This article summarizes the general information and diagnosis and assessment indices of radiation-induced heart damage and its risk factors,as well as the influencing factors for radiotherapy and effective protective measures.
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Photoautotrophic gametophyte cells of the brown macroalgae Laminaria japonica were cultivated in 500ml stirred tank photobioreactors under seven pulse feeding modes and one batch mode.It is the first time for the study of effects of the feeding time points and feeding quantity on macroalgal cell growth and nutrient consumption.Results showed that, with inoculum density of 50mg DCW/L, in modified APSW artificial seawater medium at 13℃, light intensity of 60μE/m2.s, light cycle of 16/8h L/D, aeration rate of 50ml/min, and agitation speed of 100r/min, feeding the culture with small nutrient quantity was beneficial for the synchronization between nitrate and phosphate absorption, and further for biomass production.Feeding when ambient nutrient was abundant or depleted was quite weak for large amount of biomass accumulation, which might be due to the slowing nutrient absorption, nutrient storage, or the divergence absorption between nitrate and phosphate.Feeding nutrient frequently with small quantity from mid-exponential growth of macroalgal cells, that is maintaining medium nutrient concentration between 1/3 and 1/2 of its initial concentration, was the most effective way for biomass production, with biomass increased by 12.270 times of for 51 days' cultivation.